CIMO - Capítulos de Livros
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- Applications and properties of PDMS: From biomicrofluidics to transparent face masksPublication . Lima, Rui A.; Maia, Renata; Souza, Andrews; Barbosa, Filipe; Carvalho, Denise; Carvalho, Violeta; Neves, Lucas B.; Faria, Carlos; Miranda, Inês; Sousa, Paulo; Zille, Andrea; Teixeira, Senhorinha; Minas, Graça; Machado, Lúcio; Ribeiro, J.E.Polydimethylsiloxane (PDMS) is a versatile silicone elastomer widely used in biomedical engineering due to its exceptional properties, including flexibility, chemical stability, optical transparency, biocompatibility, and ease of manufacturing. This chapter explores the unique characteristics of PDMS and its applications in biomicrofluidics and sustainable product development. PDMS is a hyperelastic material with excellent optical transparency, thermal stability, and gas permeability, making it ideal for various applications such as microfluidics, biomodels, blood analogues, implants, and organs-on-chip platforms. Its biocompatibility minimizes adverse tissue reactions, making it suitable for medical implants and skin treatments. However, its hydrophobic nature can limit certain applications, particularly in bioflow transport phenomena. To address this, surface modification techniques, such as oxygen plasma treatment, have been developed to enhance its wettability and expand its usability. In biomicrofluidics, PDMS is extensively used to create microfluidic devices that study blood cell deformability, aiding in the diagnosis of diseases like cancer, diabetes, and malaria. These devices, featuring contractions and bifurcations, provide valuable insights into microscale blood rheology and flow phenomena, improving our understanding of blood flow behavior and validating numerical simulations. The chapter also highlights the innovative use of PDMS in the production of sustainable transparent face masks. By incorporating recycled PDMS and textile fabrics, these masks feature a transparent window that allows visibility of the user’s lips, making them ideal for individuals who rely on lip-reading. The masks meet European Directive EN 14683:2019 standards, achieving level 2 certification for general public use. They offer excellent breathability, bacterial filtration efficiency, and optical transparency, while also promoting sustainability by reusing PDMS at the end of its life cycle. In conclusion, PDMS is a highly adaptable material with significant potential in biomedical applications and sustainable product development. Despite its hydrophobic nature, advancements in surface modification techniques continue to enhance its functionality, making it a valuable resource for innovative solutions in healthcare and beyond.
- Chemical Routes for the Transformation of Bio‐monomers into PolymersPublication . Gomes, Catarina P.; Bzainia, Amir; Almeida, Ayssata Patrícia da Costa Leocádia Vaz; Martins, Cláudia D.; Dias, Rolando; Costa, Mário RuiThis chapter is devoted to the analysis of the main polymerization techniques used to transform monomers derived from plant biomass into polymers. Some of these polymers,or close related macromolecules,are naturally synthesized(e.g.by bacteria) and also produced via biotechnological processes (e.g. the polyhydrox-yalkanoate P(3HP)). The goal of the analysis here presented is the description of chemical synthesis routes eventually leading to a more widespread use of these biobased and renewable polymers. Lower production prices, opportunities for functional/structural tailoring, and production scalability are potential benefits of this approach compared to the biotechnological route (when available). Given their huge volumes, environmental and economic importance as well as Worldwide expression, the exploitation of olive-tree/-oilby-products and winemak-Ing waste streams to generate biopolymers comprises two sections of this work.
- Flow visualizations in polydimethylsiloxane cerebral aneurysm biomodelsPublication . Souza, Andrews; Nobrega, Glauco; Ferrera, Conrado; Puga, Helder; Lima, Rui A.; Ribeiro, J.E.This chapter focuses on the study of intracranial aneurysms (IAs), which are localized dilations of arteries within the skull caused by weakened blood vessel walls. IAs pose a significant risk of rupture, leading to strokes with high mortality and dependency rates. The chapter emphasizes the importance of understanding the hemodynamics and geometry of blood vessels to prevent aneurysm rupture. The authors present an innovative technique for manufacturing intracranial aneurysm biomodels using Polysmooth as a sacrificial material and polydimethylsiloxane (PDMS) for the final model. PDMS is chosen for its transparency, flexibility, and ease of manufacturing, which facilitates flow visualization tests. The biomodels are designed with different geometric configurations (60° and 180° angles between inlet and outlet channels) to analyze the effects of channel geometry on blood flow patterns. The experimental setup includes high-speed video equipment, an inverted microscope, and a syringe pump to simulate blood flow using a glycerol-water solution with suspended particles. The flow visualization tests reveal differences in recirculation areas within the aneurysm based on the channel geometry, highlighting the impact of arterial structure on hemodynamics. The study concludes that the presented manufacturing technique is effective for creating realistic biomodels, enabling detailed analysis of blood flow behavior in aneurysms. This research provides valuable insights for developing numerical models and strategies to prevent aneurysm rupture
- Gamma and electron beam for food processingPublication . Antonio, Amilcar L.; Fernandes, Ângela; Pereira, Eliana; Barreira, João C.M.; Ferreira, Isabel C.F.R.; Barros, LillianHealthy and safe foods contribute to human well-being. Food processing technologies come on this behalf to make more food items available, extending their shelf-life and increasing their quality, eliminating microbiological contaminations, and increasing, in some cases, the bioavailability of some nutrients as well. One of the oldest food processes, cooking, meets these requirements.
- Inseminação ArtificialPublication . Álvaro, Armindo; Quintas, Hélder; Valentim, Ramiro;A inseminação artificial (IA) foi realizada com sucesso pela primeira vez nas aves há aproximadamente 100 anos por Ivanov. Nos galos, a recolha de sémen tornou-se mais fácil com a utilização de dispositivos desenvolvidos por Ishikawa (1930). Em 1935, Burrows e Quinn descrevem uma técnica de massagem abdominal que permitia “ordenhar” os galos. A técnica de recolha de sémen, seguida de IA, foi desenvolvida por Burrows e Quinn (1936). Todos estes investigadores são considerados os pais da IA avícola. A IA é um processo através do qual o sémen de um galo é recolhido e depois é colocado artificialmente no tracto genital de várias galinhas, com o objectivo de fecundar os oócitos II. Ela implica a recolha, avaliação, armazenamento, manuseamento e deposição dos espermatozóides (SPZ) no tracto genital da fêmea.
- Manufacture of Monomers and Precursors from Plant BiomassPublication . Gomes, Catarina P.; Bzainia, Amir; Almeida, Ayssata; Martins, Cláudia F.D.; Dias, Rolando; Costa, Mário Rui P.F.N.The use of renewable carbon sources for chemicals production plays a central role in the transition toward a circular economy using bio-based feedstocks to approach carbon neutrality andmitigate the ongoing global warming issues. Biotechnological processes, namely fermentation, are expected to succeed during the next decades in such approaches [1], but chemical routes should also represent an important share within these efforts. Development of catalysts and catalytic processes for conversion of biomass into useful chemicals and for biorefining assume an important contribution to approach this end [2].
- Six-membered ring systems: With O and/or S atomsPublication . Santos, Clementina M.M.; Silva, Artur M.S.;This chapter covers the most relevant trasformations for the synthesis of O- and S-6-membered heterocycles, published in 2024. This personal overview is focused on the new achievements made on the synthesis of several natural compounds, specific reactions and reagents for the preparation of natural and synthetic pyrans, chromenes and chromans, isochromenes and isochromans, pyranones, coumarins and isocoumarins, chromones and chromanones, xanthenes and xanthones, thiopyrans and analogues, dioxanes, trioxanes, tetraoxanes, dithiins, and also oxathianes.