1,535 research outputs found

    Biomass conversion to bioplastics: determination of thermodynamic properties and equilibrium of the catalysed sorbitol-to-isosorbide double dehydration reaction

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    Treballs Finals de Grau d'Enginyeria Química, Facultat de Química, Universitat de Barcelona, Curs: 2022-2023, Tutors: Eliana Ramírez Rangel, Javier Tejero SalvadorThis work, which is part of a larger study, is related to the production of polymers and plastics from biomass (known as biopolymers and bioplastics) as an alternative to the use of fossil fuels derived from petroleum as raw materials on an industrial scale. Specifically, it focuses on the synthesis of isosorbide (IB) from sorbitol (SOH). Isosorbide is a molecule that has countless applications and uses. It is a monomer for various bioplastics such as poly-(isosorbide carbonate) (PIC), and it participates in the synthesis of pharmaceutical industry or cosmetic formulation intermediates or products. It can also function as an additive for biofuels or various surfactants. The proposed reaction mechanism to produce isosorbide from sorbitol is the twofold dehydration of sorbitol through 1,4-sorbitan (1,4-ST), catalysed by an acid catalyst. This catalysis is provided by acid solid catalysts, for example ion exchange resins. This study is dedicated to the experimental determination of the equilibrium constant of the aforementioned reactions over the temperature range 130 - 190 °C, as well as the determination of the thermodynamic properties of the system within this temperature range, including enthalpy, entropy, and Gibbs free energy. These thermodynamic properties will be compared with the existing literature as well as with those obtained through estimation from studies conducted in the same research group. The enthalpy and entropy changes of the sorbitol dehydration reactions were estimated to be -(7 ± 2) kJ/mol and (15 ± 4) J/(mol·K) and (23 ± 4) kJ/mol and (73 ± 9) J/(mol·K) for 1,4-ST and 2,5-ST formation respectively. As for the IB formation, enthalpy and entropy changes were set to be (15 ± 5) kJ/mol and (46 ± 11). Being the SOH-to-1,4-ST dehydration exothermic and the SOH-to-2,5-ST and 1,4-ST-to-IB reactions endothermi

    The i* framework for goal-oriented modeling

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    The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-319-39417-6i* is a widespread framework in the software engineering field that supports goal-oriented modeling of socio-technical systems and organizations. At its heart lies a language offering concepts such as actor, dependency, goal and decomposition. i* models resemble a network of interconnected, autonomous, collaborative and dependable strategic actors. Around this language, several analysis techniques have emerged, e.g. goal satisfaction analysis and metrics computation. In this work, we present a consolidated version of the i* language based on the most adopted versions of the language. We define the main constructs of the language and we articulate them in the form of a metamodel. Then, we implement this version and a concrete technique, goal satisfaction analys is based on goal propagation, using ADOxx. Throughout the chapter, we used an example based on open source software adoption to illustrate the concepts and test the implementation.Peer ReviewedPostprint (author's final draft

    Uso de dispositivos vasculares bioabsorbibles en el tratamiento de la reestenosis intrastent

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    Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Medicina, Departamento de Medicina. Fecha de lectura: 09-04-202

    FEASIBILITY STUDY FOR THE CREATION OF AN ENVIRONMENTAL CONSULTING FIRM IN THE OIL & GAS SECTOR, UNDER THE PMI’s GUIDELINES

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    Uno de los sectores de mayor crecimiento económico en el país es el del aprovechamiento de recursos hidrocarbunifereos (Petróleo y Gas), sector se ha consolidado a partir de los cambios en la legislación que el gobierno nacional ha venido haciendo desde el año 2003, ofreciendo ventajas competitivas como un gran potencial sin explotar por ser descubierto, una excelente ubicación geográfica, una extensa infraestructura de transporte, mano de obra altamente calificada tanto técnica como profesional, una estabilidad económica mejorada al ofrecer a los inversionistas un entorno empresarial estable y predecible así como un sistema legal sólido y atractivas condiciones de inversión.One of the fastest growing economic sectors in our country is the exploitation of oil & gas resources, this industry has been consolidated because of some changes in the law that the national government has been doing since 2003, offering competitive advantages as a large unexploded potential to be discovered, an excellent geographical location, extensive transportation infrastructure, technical and professional highly skilled workers, an improved economic stability offers to investors a stable and predictable business environment, as well as economic stability like a solid legal system and attractive investment conditions
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