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Flexographic Printed Flexible Thermochromic Stickers for Smart Sensing Applications
Publication . Morais, M.; Figueira, J.; Corvo, M. C.; Peixoto, M.; Oliveira, Duarte Belo de; Gonçalves, A.; Fortunato, E.; Martins, R.; Carlos, E.; Pinto, J. V.; DCM - Departamento de Ciência dos Materiais; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); John Wiley and Sons Ltd
The growing demand for thermochromic materials in areas such as food packaging requires the development of fast-response and extended-life materials. The use of metal cation-ionic liquid complexes is increasing due to the easiness to tailor their properties, leading to changes in thermochromic response. This work presents the synthesis and introduction of thermochromic 1-butyl-3-methylimidazolium chloride and 4-chloronickelate ([BMIm]2[NiCl4]) complexes into water-based inks. Formulations with varying concentrations of complexes (10–40 wt.%) are printed on tags thorugh a roll-to-roll process and tested between 30–45 °C. Also, films with one to five layers are analyzed for color contrast and different encapsulating materials are studied to improve the thermochromic films' robustness. The optimal films, with three layers of ink with 40 wt.% complexes encapsulated with Fixomull Transparent present enhanced color contrast and fast response time. Red-green-blue analysis is performed on these films, revealing a blue/red ratio of 1.7 after heating at 40 °C for 30 min. This work paves the way for developing flexible stickers with fast response and high contrast. The innovative and straightforward thermochromic inks' production process and compatibility with large-scale manufacturing show their promising future as cost-effective stickers for smart packaging applications, such as visual indicators of ideal food consumption temperatures.
New insights in uranium bioremediation by cytochromes of the bacterium Geotalea uraniireducens
Publication . Almeida, Alexandre; Turner, David L.; Silva, Marta A.; Salgueiro, Carlos A.; Instituto de Tecnologia Química e Biológica António Xavier (ITQB); UCIBIO - Applied Molecular Biosciences Unit; DQ - Departamento de Química; Faculdade de Ciências e Tecnologia (FCT); ASBMB - American Society for Biochemistry and Molecular Biology
The bacterium Geotalea uraniireducens, commonly found in uranium-contaminated environments, plays a key role in bioremediation strategies by converting the soluble hexavalent form of uranium (U(VI)) into less soluble forms (e.g., U(IV)). While most of the reduction and concomitant precipitation of uranium occur outside the cells, there have been reports of important reduction processes taking place in the periplasm. In any case, the triheme periplasmic cytochromes are key players, either by ensuring an effective interface between the cell's interior and exterior or by directly participating in the reduction of the metal. Therefore, understanding the functional mechanism of the highly abundant triheme cytochromes in G. uraniireducens’ is crucial for elucidating the respiratory pathways in this bacterium. In this work, a detailed functional characterization of the triheme cytochromes PpcA and PpcB from G. uraniireducens was conducted using NMR and visible spectroscopy techniques. Despite sharing high amino acid sequence identity and structural homology with their counterparts from Geobacter sulfurreducens, the results showed that the heme reduction potential values are less negative, the order of oxidation of the hemes is distinct, and the redox and redox-Bohr network of interactions revealed unprecedented functional mechanisms in the cytochromes of G. uraniireducens. In these cytochromes, the reduction potential values of the three heme groups are much more similar, resulting in a narrower range of values, that facilitates directional electron flow from the inner membrane, thereby optimizing the uranium reduction.
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Fundação para a Ciência e a Tecnologia
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Concurso para Financiamento de Projetos de Infraestruturas de Investigação inseridas no Roteiro Nacional de Infraestruturas de Investigação de Interesse Estratégico
Número da atribuição
PINFRA/22161/2016