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Center for Natural Resources and Environment
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Potential of supercritical fluid myrtle extracts as an active ingredient and co-preservative for cosmetic and topical pharmaceutical applications
Publication . Pereira, Paula; Mauricio, Elisabete Muchagato; Duarte, Maria Paula; Lima, Katelene; Fernandes, Ana S.; Bernardo-Gil, Gabriela; Cebola, Maria João; MEtRICS - Centro de Engenharia Mecânica e Sustentabilidade de Recursos; Elsevier BV
This study investigated the applications of a myrtle extract obtained by supercritical fluid extraction (SFE), a technique considered environmentally friendly, as a possible antimicrobial ingredient in cosmetic and pharmaceutical formulations. The supercritical fluid extract was obtained at 230 bar and 45 °C, for 2 h, with a flow of CO2 of 0.3 kg h−1. A cosolvent (ethanol) was also used, with a flow 0.09 kg h−1. The extracts thus obtained were tested against seven Gram-positive bacteria and one yeast using the well diffusion and the broth dilution techniques. The results showed that the myrtle extract exhibits good antibacterial activity against all the bacteria strains studied and is superior to most of those obtained by conventional extraction methods. Antifungal activity was also present but at a lesser extent. Cell viability studies were carried out by exposing HaCat cells to a range of extract concentrations, from 0.1 μg/mL up to 60 μg/mL for 24 h, using the MTT assay. The Salmonella mutagenicity assay was applied to evaluate the mutagenicity and antimutagenicity of the extract. The results obtained suggest that the myrtle extract obtained using a green solvent, supercritical CO2, is safe and could reduce the genotoxic damage induced by reactive oxygen species (ROSs).
Decision making based on hybrid modeling approach applied to cellulose acetate based historical films conservation
Publication . Al Mohtar, Abeer; Pinto, Moisés L.; Neves, Artur; Nunes, Sofia; Zappi, Daniele; Varani, Gabriele; Ramos, Ana Maria; Melo, Maria João; Wallaszkovits, Nadja; Lahoz Rodrigo, Juan Ignacio; Herlt, Kerstin; Lopes, João; LAQV@REQUIMTE; DCR - Departamento de Conservação e Restauro; Nature Publishing Group
Preserving culture heritage cellulose acetate-based historical films is a challenge due to the long-term instability of these complex materials and a lack of prediction models that can guide conservation strategies for each particular film. In this work, a cellulose acetate degradation model is proposed as the basis for the selection of appropriate strategies for storage and conservation for each specimen, considering its specific information. Due to the formulation complexity and diversity of cellulose acetate-based films produced over the decades, we hereby propose a hybrid modeling approach to describe the films degradation process. The problem is addressed by a hybrid model that uses as a backbone a first-principles based model to describe the degradation kinetics of the pure cellulose diacetate polymer. The mechanistic model was successfully adapted to fit experimental data from accelerated aging of plasticized films. The hybrid model considers then the specificity of each historical film via the development of two chemometric models. These models resource on gas release data, namely acetic acid, and descriptors of the films (manufacturing date, AD-strip value and film type) to assess the current polymer degradation state and estimate the increase in the degradation rate. These estimations are then conjugated with storage conditions (e.g., temperature and relative humidity, presence of adsorbent in the film’s box) and used to feed the mechanistic model to provide the required time degradation simulations. The developed chemometric models provided predictions with accuracy more than 87%. We have found that the storage archive as well as the manufacturing company are not determining factors for conservation but rather the manufacturing date, off gas data as well as the film type. In summary, this hybrid modeling was able to develop a practical tool for conservators to assess films conservation state and to design storage and conservation policies that are best suited for each cultural heritage film.
Durability assessment of external thermal insulation composite systems in urban and maritime environments
Publication . Parracha, J. L.; Borsoi, G.; Veiga, R.; Flores-Colen, I.; Nunes, L.; Viegas, C. A.; Moreira, L. M.; Dionísio, A.; Gomes, M. Glória; Faria, P.; CERIS - Polo NOVA; DEC - Departamento de Engenharia Civil; Elsevier
External Thermal Insulation Composite Systems (ETICS) are multilayer solutions which provide an enhanced thermal performance to the building envelope. However, significant anomalies can be detected on ETICS facades, in some cases shortly after the application of these systems. This study intends to evaluate and compare the durability of six commercially available ETICS after two years of outdoor exposure at both urban and maritime conditions in Portugal. The systems were characterized by means of non-destructive testing (i.e., visual and microscopic assessment, water transport properties, thermal conductivity, surface roughness), thus allowing to evaluate the performance loss throughout natural aging. The bio-susceptibility and aesthetic properties (color and gloss) were also investigated. Results showed that the performance and durability of the complete system is significantly affected by the rendering system formulation. The lime-based specimens obtained the highest rate of mold development after one year of aging in a maritime environment, becoming considerably darker and with lower surface gloss. Fungal analysis of this darkish stained area indicated the presence of mold species of the genera Alternaria, Didymella, Cladosporium and Epicoccum, and yeasts of the genera Vishniacozyma and Cystobasidium. An increase of both capillary water absorption and water vapor permeability was also registered for the aged lime-based specimens. Acrylic-based systems obtained lower capillary water absorption after aging and greater dirt deposition on their surfaces, especially in urban conditions. These systems had also higher color variation and surface gloss decrease and slightly higher mold growth, when compared with those aged in a maritime environment. Finally, no mold growth was detected on the silicate-based specimens after two years of aging. However, these specimens obtained higher capillary water absorption and lower vapor permeability after aging, possibly leading to moisture accumulation within the system. Results contribute towards the development of ETICS with enhanced performance and durability.
Iron(III) based Metal-Organic Frameworks in cellulose acetate film preservation
Publication . Mohtar, Abeer Al; Severino, Maria Inês; Tignol, Pierre; Ranza, Luigi; Neves, Artur; Nouar, Farid; Pimenta, Vanessa; Lopes, João; Ramos, Ana Maria; Rodrigo, Juan Ignacio Lahoz; Melo, Maria João; Wallaszkovits, Nadja; Pinto, Moisés L.; Dupont, Anne Laurence; Serre, Christian; Lavédrine, Bertrand; LAQV@REQUIMTE; DCR - Departamento de Conservação e Restauro; DQ - Departamento de Química; Elsevier
Low-temperature storage to slow down degradation is accepted by the film conservation community. Still, this solution prohibits public access, is price-sensitive, has high energy costs, and there are concerns about their effects on the physical stability and material lifetime. In this research, a smart solution is developed based on the selective capture of acetic acid produced by the cellulose acetate polymer. This innovative approach is based on Metal-Organic Frameworks (MOFs) for acetic acid adsorption, specifically a highly selective porous iron(III) based MOF, MIL-100(Fe), which was synthesized using a green approach. The stability of MIL-100(Fe), under acetic acid exposure, was demonstrated by accelerated aging experiments, with no noticeable changes in crystallinity and/or porosity as deduced from powder X-ray diffraction analysis, infrared spectroscopy, thermogravimetric analysis, nitrogen porosimetry, and electron microscopy. Compatibility tests with the artefacts were performed to prove the safety of the MIL-100(Fe) to the artefacts. A field application in a demonstration prototype (smart box) was performed at Institut Valencià de Cultura. A recently developed hybrid model provided recommendations on the quantity of adsorbents to use in the smart box. Good agreement was observed between the model predictions and the in-field experimental results, which validated the model application. The model predicted that the new adsorbent (5% of the film's weight, replaced every 10 years, at 16°C or 22°C) extends the film's lifetime equivalently to cold storage (5°C). Finally, environmental impact assessment and life cycle analysis were performed to compare the two preservation approaches. The new approach based on this Fe-MOF yielded an average reduction of carbon footprint related to movie film preservation of about 50% considering the current European Union (EU) energy mix and about 40% considering the 2030 EU energy mix (where a transition towards renewable energy is expected). The proposed innovative technology represents a robust solution towards efficient and more sustainable film preservation while significantly contributing to moving toward climate transition objectives in the culture heritage sector.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
6817 - DCRRNI ID
Número da atribuição
UIDB/04028/2020