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- In Vitro Evaluation of the Photoreactivity and Phototoxicity of Natural Polyphenol AntioxidantsPublication . Aguiar, Brandon; Carmo, Helena; Garrido, Jorge; Sousa Lobo, José M.; Almeida, Isabel F.Polyphenols are a large family of natural compounds widely used in cosmetic products due to their antioxidant and anti-inflammatory beneficial properties and their ability to prevent UV radiation-induced oxidative stress. Since these compounds present chromophores and are applied directly to the skin, they can react with sunlight and exert phototoxic effects. The available scientific information on the phototoxic potential of these natural compounds is scarce, and thus the aim of this study was to evaluate the photoreactivity and phototoxicity of five phenolic antioxidants with documented use in cosmetic products. A standard ROS assay was validated and applied to screen the photoreactivity of the natural phenolic antioxidants caffeic acid, ferulic acid, p-coumaric acid, 3,4-dihydroxyphenylacetic acid (DOPAC), and rutin. The phototoxicity potential was determined by using a human keratinocyte cell line (HaCaT), based on the 3T3 Neutral Red Uptake phototoxicity test. Although all studied phenolic antioxidants absorbed UV/Vis radiation in the range of 290 to 700 nm, only DOPAC was able to generate singlet oxygen. The generation of reactive oxygen species is an early-stage chemical reaction as part of the phototoxicity mechanism. Yet, none of the studied compounds decreased the viability of keratinocytes after irradiation, leading to the conclusion that they do not have phototoxic potential. The data obtained with this work suggests that these compounds are safe when incorporated in cosmetic products.
- Ciprofloxacin and carbamazepine adsorption on activated carbons produced from leather residuesPublication . Marques, David; Mota, Salomé; Freitas, Maria Madalena; Silva, Paula CristinaCiprofloxacin and carbamazepine adsorption was studied using an activated carbon produced from leather residues (wet white shavings) and a commercially available activated carbon (Norit ROW 0.8) and the effect of pH level was studied. The activated carbon produced from wet white shavings showed better results due to its higher specific surface area, confirming that leather residues are a viable precursor for the preparation of activated carbons for the adsorption of these chemicals. The effect of pH on the AC adsorption capacity was not significant in the case of carbamazepine, however lower pH led to higher adsorption capacities for ciprofloxacin.
- Energy and exergy analysis of co-gasification of crude glycerol and animal fat mixturesPublication . Almeida, Ana; Pilão, Rosa Maria; Ramalho, Elisa; Pinho, CarlosThis work presents an energy and exergy analysis of co-gasification tests of crude glycerol and animal fat mixtures, in order to obtain first and second law efficiencies, the last ones representing a novelty in the field of gasification technology. Mixtures with 5% (w/w) of dry animal fat, 57% (w/w) of dry treated crude glycerol and 38% (w/w) of water were studied in a fixed bed down flow gasification reactor at 800°C and 900°C. The increase of gasification temperature seems not to affect the energy and exergy yields of the overall process.
- Editorial: Biomass, Bioenergy and Biofuels for Circular BioeconomyPublication . Caetano, Nídia S.; Xu, Suyun; Banu, Jeyakumar Rajesh; Sani, Rajesh K.; Karthikeyan, Obulisamy ParthibaThe huge demand for energy and products, mostly based on fossil fuels, have caused severe environmental impacts, that are based on pollution, greenhouse gas (GHG) emissions, and finally of climate changes. While energy can be supplied from different renewable sources, such as solar, wind or hydro energy, they are intrinsically impossible or hard to control, or dependent on climatic conditions that are becoming more and more unpredictable. In this context, biomass has come, once more, as one of the potential solutions to add to the renewable energy mix.
- Methodology for the decision-making process in Social District Heating implementationPublication . Alonso, Rita; Azevedo, João; Martins, FlorindaDistrict heating is a centralized energetic system, capable of providing heat to different structures. This technology helps achieving energetic efficiency with a high fuel flexibility, enabling the use of various renewable sources, which will lead to a lower pollution potential. Beside the environmental perspective, these systems show a great ability concerning the social context. Benefits such as, tackling fuel poverty, increasing employment and population in areas suffering from desertification, along with forest fire prevention, lead to the social perspective as the primary motivation for the implementation of these systems, creating the concept of Social District Heating (SDH). Therefore, this paper developed a decision support tool to prioritize locations in the most need of an SHD, with the necessary features to include this technology in its area. A methodology intended to assess quantitative and qualitative variables is presented, step by step, evaluating each location relatively to community aspects, background context and council power criteria. The results presented enhance more than one location, however one appears as the most appropriate for the SDH implementation.
- Melanoma in the Eyes of MechanobiologyPublication . Brás, M. Manuela; Radmacher, Manfred; Sousa, Susana R.; Granja, Pedro L.Skin is the largest organ of the human body with several important functions that can be impaired by injury, genetic or chronic diseases. Among all skin diseases, melanoma is one of the most severe, which can lead to death, due to metastization. Mechanotransduction has a crucial role for motility, invasion, adhesion and metastization processes, since it deals with the response of cells to physical forces. Signaling pathways are important to understand how physical cues produced or mediated by the Extracellular Matrix (ECM), affect healthy and tumor cells. During these processes, several molecules in the nucleus and cytoplasm are activated. Melanocytes, keratinocytes, fibroblasts and the ECM, play a crucial role in melanoma formation. This manuscript will address the synergy among melanocytes, keratinocytes, fibroblasts cells and the ECM considering their mechanical contribution and relevance in this disease. Mechanical properties of melanoma cells can also be influenced by pigmentation, which can be associated with changes in stiffness. Mechanical changes can be related with the adhesion, migration, or invasiveness potential of melanoma cells promoting a high metastization capacity of this cancer. Mechanosensing, mechanotransduction, and mechanoresponse will be highlighted with respect to the motility, invasion, adhesion and metastization in melanoma cancer.
- Preface for CEEPE 2020 ProceedingsPublication . Caetano, NídiaThe 3rd International Conference on Energy, Electrical, and Power Engineering (CEEPE) was planned to be held in April 24-26, 2020, in Chongqing, China, and was co-sponsored by the University of Electronic Science and Technology of China; Wuhan University, China; Shandong University, China; South Asia Institute of Science and Engineering (SAISE) and IEEE PES Chongqing Chapter.
- Reproductive cycle progression arrest and modification of cell morphology (shape and biovolume) in the alga Pseudokirchneriella subcapitata exposed to metolachlorPublication . Machado, Manuela Dias; Soares, Eduardo V.Metolachlor (MET) is an herbicide widely used and frequently found (at μg L-1) in aquatic systems. This work aimed to study the modes of action of MET on the green microalga Pseudokirchneriella subcapitata. Algae exposed to 115 or 235 μg L-1 MET, for 48 or 72 h, presented a reduction of metabolic activity, chlorophyll a and b content and photosynthetic efficiency. The exposure to 115 or 235 μg L-1 MET also induced growth yield reduction, mean cell biovolume increase and alteration of the typical algae shape (cells lunate or helically twisted) to "French croissant"-type; at these MET concentrations, algal population was mainly composed by multinucleated cells (≥ 4 nuclei), which suggest that MET impairs the normal progression of the reproductive cycle but did not hinder nuclear division. The accumulation of multinucleated cells seems to be the consequence of the incapacity of the parent cell to release the autospores. In conclusion, MET disrupts the physiology of P. subcapitata cells; the disturbance of the progression of the reproductive cycle should be in the origin of growth slowdown (or even its arrest), increase of mean cell biovolume and modification of algal shape. This work contributed to elucidate, in a systematically and integrated way, the toxic mechanism of MET on the non-target organism, the alga P. subcapitata.
- Biotechnological potential of Phaeodactylum tricornutum for biorefinery processesPublication . Branco-Vieira, Monique; San Martin, Sergio; Agurto, Cristian; Freitas, Marcos A.V.; Martins, António A.; Mata, Teresa M.; Caetano, NídiaMicroalgae are a rich source of proteins, carbohydrates and lipids, among other components, and thus, are considered to be the next generation biomass. However, in order to enhance the economic viability of its industrial production, all biomass components need to be valorized, requiring a multi-product biorefinery. Thus, this work proposes and conceptually analyses biorefinery processes for valorizing Phaeodactylum tricornutum for biofuels and high-value compounds, based on real data from a pilot-scale process. The algal biomass was biochemically characterized and the production was scaled-up to an industrial approach to analyze three biorefinery configurations, based on a 18 ton·year−1 of microalga biomass. The biomass revealed a composition of 7.85 wt% carbohydrates, 38.40 wt% proteins, 9.08 wt% lipids, 0.86 wt% fucoxanthin and 5.19 wt% biosilica. The biorefinery process addressed for biofuels production has an estimated annual production of 1.72, 0.35 and 1361 m3·year−1 of respectively biodiesel, bioethanol and biomethane. The biorefinery addressed for high-value compounds yields 0.18, 0.93 and 6.95 ton·year−1 of respectively fucoxanthin, biosilica and protein. The biorefinery designed for valorizing full microalgae biomass, showed to be more beneficial for promoting a circular economy. Biorefinery approach is useful for making sound and profitable decisions regarding microalgae bioproducts.
- Fish Oil Enzymatic Esterification for Acidity ReductionPublication . Mata, Teresa M.; Correia, Daniela; Andrade, Soraia; Casal, Susana; Ferreira, Isabel M. P. L. V. O.; Matos, Elisabete; Martins, António A.; Caetano, NídiaThe reduction of the fish oil acidity is a significant problem in the rendering industry, as the oil’s range of applications and market value strongly depend on this parameter. In particular, the lower the acidity, the larger the oil’s market value. This work aims to study the potential of enzymatic esterification for reducing the fish oil acidity, by converting the free fatty acids into esters. Thus, four commercial lipases were used and a parametric study was performed to identify the best operating conditions, varying the reaction temperature, enzyme/oil mass ratio and alcohol/FFA mass ratio. All experiments were performed in duplicate with a very good reproducibility of results. Results showed that Lipozyme TL 100L contributed to greater acidity reduction (75% from an initial acid value of 10–14 mg KOH/g oil) for esterification at 40 °C, using ethanol 96% v/v, enzyme/oil and alcohol/FFA mass ratios of 0.01 and 3.24 w/w, respectively, reaching 3.13 mg KOH/g oil of final acid value or 1.57% FFA content. The reaction kinetics were also studied and it was found that a second order rate law as a function of the alcohol and oil concentrations is more adequate, with 35.44 kJ/mol of activation energy and 1.94 × 103 L mol− 1 min− 1 of pre-exponential factor. In conclusion, this work shows that the enzymatic esterification to reduce the fish oil acidity is technically feasible, increasing its market value.