Browsing by Author "Nunes, Paulo"
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- Antifungal and Antioxidant Properties of Chitosan Polymers Obtained from Nontraditional Polybius henslowii SourcesPublication . Avelelas, Francisco; Horta, André; Pinto, Luís F.V.; Marques, Sónia Cotrim; Nunes, Paulo; Pedrosa, Rui; Leandro, Sérgio MiguelChitin was extracted from Polybius henslowii, a swimming crab, captured in large quantities throughout the Portuguese coast by purse seine vessels as bycatch. After standard chitin extraction procedures, water-soluble chitosan products were obtained via two di erent methods: (1) N-acetylation with the addition of acetic anhydride and (2) a reaction with hydrogen peroxide. The chemical structure and molecular weight of chitosan derivatives, water-soluble chitosan (WSC) and chitooligosaccharides (COS), were confirmed by Fourier Transform Infrared Spectroscopy (FT-IR) and gel permeation chromatography (GPC).Antioxidant and metal chelation activities were evaluated, and the growth inhibition capacity was tested on four phytopatogens. The chitooligosaccharides from pereopods (pCOS) and shell body parts (sCOS) inhibited all fungal species tested, particularly Cryphonectria parasitica with 84.7% and 85.5%, respectively. Both radical scavenging and antifungal activities proved to be dose-dependent. Chitooligosaccharides with a low molecular weight (2.7, 7.4, and 10.4 Kg mol1) showed the highest activity among all properties tested. These results suggested that chitosan derivatives from P. henslowii raw material could potentially be used against phytopathogens or as ingredient in cosmetics and other products related to oxidative stress.
- Effects of different drying conditions on the rehydration ratio and water holding capacity properties in three different species of algae Ulva lactuca, Codium vermilara and Codium tomentosumPublication . Rodrigues, Sidónio; Afonso, Clélia; Mouga, Teresa; Nunes, PauloOver the last years, algae have been increasingly used in Human food due their rich chemical and nutritional composition, particularly the high supply of essential nutrients to the human body such as protein and dietary fiber. Dietary fiber can be divided into two different types: soluble and insoluble. The characteristics of soluble dietary fiber are related to some physical and chemical properties such as rehydration ratio and water holding capacity and are important in assigning the functional and organoleptic properties and in preventing some human pathologies such as cardiovascular disease and obesity. The present study aimed to investigate the influence of different drying conditions on the rehydration ratio and water holding capacity of three green algae, Codium vermilara, Codium tomentosum and Ulva lactuca. The methods used for the determination of water retention capacity and rehydration ratio were similar to those used in previous studies (Susuki, T. et al., 1996). The algae were processed in a tray dryer and the drying conditions were: Temperature: 30ºC and 40ºC; Relative Humidity: 28%47% ; air velocity 1,9 m/s. In this work, it was concluded that higher drying temperature conditions originate lower rehydration ratio and consequent lower water holding capacity possibly due to a higher physical damage in the algae tissues. It was also observed that both Codium species have higher values for these two parameters than Ulva lactuca, under the same rehydration conditions.
- Evaluating cybersecurity attitudes and behaviors in Portuguese healthcare institutionsPublication . Nunes, Paulo; Antunes, Mário; Silva, CarinaThe growing digitization of healthcare institutions and its increasing dependence on Internet infrastructure has boosted the concerns related to data privacy and confidentiality. These institutions have been challenged with specific issues, namely the sensitivity of data, the specificity of networked equipment, the heterogeneity of healthcare professionals (nurses, doctors, administrative staff and other) and the IT skills they have.
- Excessive daytime sleepiness in drivers of heavy vehiclesPublication . Nunes, Paulo; Carvalho, Lucinda S.A.; Pereira, Alexandre J.M.Introduction: Excessive daytime sleepiness is an entity that has a negative impact on physical and cognitive performance, since it reduces the individual's ability to respond to stimuli. Professional drivers are undoubtedly a class exposed to this entity, endangering their life and others. Objective: To investigate the prevalence of Excessive Daytime Sleepiness in drivers of heavy trucks and passenger vehicles, comparing it with accidents/near misses accidents and also to relate these variables with the type of vehicle. Methods: This study evaluated 148 drivers, of which 68 were drivers of heavy trucks vehicles, 58 of passenger vehicles and 22 of both types of trucks. Both Epworth Sleepiness Scale and a questionnaire to assess sleeping habits and driving habits were used. Results: The prevalence of sleepiness in drivers is 37,8 % and it was correlated with the total time in bed (r = -0.169, p = 0.040) and with the time of driving of heavy trucks (r = 0.151, p = 0.068). It was found that 14.2 % of accidents and 27.8 % of near misses accidents were due to sleepiness. Highly significant differences in sleepiness and near misses were found (p < 0.001). There was dependence between the type of vehicle and accidents (p = 0.046). Conclusion: In the group of evaluated drivers there is Excessive Daytime Sleepiness, which leads to the significantly increasing risk of accidents/near misses accidents, as well as a higher incidence of accidents in truck drivers compared to drivers of passenger vehicles.
- Light field HEVC-based image coding using locally linear embedding and self-similarity compensated predictionPublication . Monteiro, Ricardo; Lucas, Luis; Conti, Caroline; Nunes, Paulo; M. M. Rodrigues, Nuno; Faria, Sergio; Pagliari, Carla; Silva, Eduardo da; Soares, LuisLight field imaging is a promising new technology that allows the user not only to change the focus and perspective after taking a picture, as well as to generate 3D content, among other applications. However, light field images are characterized by large amounts of data and there is a lack of coding tools to efficiently encode this type of content. Therefore, this paper proposes the addition of two new prediction tools to the HEVC framework, to improve its coding efficiency. The first tool is based on the local linear embedding-based prediction and the second one is based on the self-similarity compensated prediction. Experimental results show improvements over JPEG and HEVC in terms of average bitrate savings of 71.44% and 31.87%, and average PSNR gains of 4.73dB and 0.89dB, respectively.