6 research outputs found

    Ensayo aleatorizado del cierre de orejuela izquierda vs varfarina para la prevenci├│n de accidentes cerebrovasculares tromboemb├│licos en pacientes con fibrilaci├│n auricular no relacionada con valvulopat├şa. Estudio PREVAIL

    Get PDF
    The successful application of poly┬ş(<i>N</i>-vinylcaprolactam)-based microgels requires a profound understanding of their synthesis. For this purpose, a validated process model for the microgels synthesis by precipitation copolymerization with the cross-linker <i>N</i>,<i>N</i>ÔÇ▓-methylenebis┬ş(acrylamide) is formulated. Unknown reaction rate constants, reaction enthalpies, and partition coefficients are obtained by quantum mechanical calculations. The remaining parameter values are estimated from reaction calorimetry and Raman spectroscopy measurements of experiments with different monomer/cross-linker compositions. Because of high cross-propagation reaction rate constants, simulations predict a fast incorporation of the cross-linker. This agrees with reaction calorimetry measurements. Furthermore, the gel phase is predicted as the major reaction locus. The model is utilized for a prediction of the internal particle structure regarding its cross-link distribution. The highly cross-linked core reported in the literature corresponds to the predictions of the model

    Optimization of Multiproduct Biorefinery Processes under Consideration of Biomass Supply Chain Management and Market Developments

    No full text
    Even though a shift from conventional to renewable resources is often envisaged, lignocellulosic biorefinery concepts struggle with economic viability and sustainability. In order to overcome these barriers, a full analysis from biomass supply chain, process performance optimization, and product-portfolio selection is targeted. Addressing the economic viability and sustainability already at an early process development stage when only limited knowledge is available, Process Network Flux Analysis (PNFA) [Ulonska et al., <i>AIChE J.</i> <b>2017</b>, <i>62</i>, 3096ÔÇô3108] is capable of systematically identifying the most valuable processing pathways. This enables a first performance ranking based on the profit or global warming potential of pathways, thereby accelerating process development. While so far only processing networks have been considered, the methodology is herein extended to consider biomass supply chain optimization and market-dependent price developments such that all main influencing factors are considered simultaneously. The extended methodology is validated identifying reasonable plant locations in North Rhine-Westphalia, Germany. Enhancing economic viability of the best performing biofuel ethanol, a multiproduct biorefinery is targeted coproducing value-added chemicals. Herein, a coproduction of iso-butanol raises the profit significantly: a mass ratio of at most 1.9 (ethanol:iso-butanol) is required to break even

    Mapping of the optimized model to the PKN.

    No full text
    <p>Mapping of the optimization results to the PKN by removing the compartmentalized components. Reactions within the same compartment are plotted in blue and were not included in the optimization procedure. Reactions in black are the ones whose parameters were interrogated. Their opacity corresponds to their activity in the optimized model, with reactions that propagate more signal downstream being more opaque than the rest.</p