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Percorrer por autor "Ferreira, Jessica"

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  • Argan oil as a rich source of linoleic fatty acid for dietetic structured lipids production
    Publication . Simões, Tiago; Ferreira, Jessica; Lemos, Marco F.L.; Augusto, Ana; Félix, Rafael; Silva, Susana F.J.; Ferreira-Dias, Suzana; Tecelão, Carla
    Argan oil is rich in long-chain unsaturated fatty acids (FA), mostly oleic and linoleic, and natural antioxidants. This study addresses the production of low-calorie structured lipids by acidolysis reaction, in a solvent-free system, between caprylic (C8:0; system I) or capric (C10:0; system II) acids and argan oil, used as triacylglycerol (TAG) source. Three commercial immobilized lipases were tested: Novozym® 435, Lipozyme® TL IM, and Lipozyme® RM IM. Higher incorporation degree (ID) was achieved when C10:0 was used as acyl donor, for all the lipases tested. Lipozyme® RM IM yielded the highest ID for both systems (28.9 +- 0.05 mol.% C10:0, and 11.4 +- 2.2 mol.% C8:0), being the only catalyst able to incorporate C8:0 under the reaction conditions for biocatalyst screening (molar ratio 2:1 FA/TAG and 55ºC). The optimal conditions for Lipozyme® RM IM in system II were found by response surface methodology (66ºC; molar ratio FA/TAG of 4:1), enabling to reach an ID of 40.9 mol.% of C10:0. Operational stability of Lipozyme® RM IM in system II was also evaluated under optimal conditions, after eight consecutive 24 h-batches, with biocatalyst rehydration between cycles. The biocatalyst presented a half-life time of 103 h.
    2021Artigo científico Acesso aberto Ver mais
  • Performance of Hash Functions in Blockchain Applied to IoT Devices
    Publication . Ferreira, Jessica; Antunes, Mário; Zhygulskyy, Mykyta; Frazão, Luis
    The IoT (Internet of Things) is a network composed of several devices (things) connected to the Internet and to each other. IoT services are increasingly growing and are allowing companies to deploy scalable solutions with reduced costs and instantaneous data access. These solutions require seamless authentication, data privacy, security, robustness against attacks, easy deployment, and self-maintenance. Such requirements can be given to a company's IoT solution by applying blockchain technology. This paper analyzes the blockchain technology and the advantages and challenges behind its implementation in an IoT environment. A blockchain in IoT scenario was developed to evaluate the performance of different cryptographic hash functions in the IoT device RaspberryPi. Conclusions were drawn when it comes to the viability of some hash functions mainly based on the low resource characteristic shared by the IoT devices, which compromises the performance of the hash function.
    2019-06Comunicação em conferência Acesso aberto Ver mais