Browsing by Issue Date, starting with "2017-03"
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- Prática pedagógica em Engenharia Informática: análise da utilização do Wolfram|AlphaPublication . Martins, Paula Ventura; Conceição, Ana C.A utilização em sala de aula do motor de conhecimento computacional Wolfram|Alpha, desenvolvido pela Wolfram Research, permite uma abordagem interativa e dinâmica no ensino de conceitos e propriedades fundamentais nas áreas do Cálculo Diferencial e do Cálculo Integral, proporcionando um contexto de ensino-aprendizagem onde alunos e professores são igualmente convidados a contribuir. Sendo uma ferramenta de acesso livre decidiu-se aplicar em aulas de Análise Matemática para alunos inscritos numa licenciatura em Engenharia Informática com o objetivo de consolidar conteúdos programáticos adquiridos, em outras unidades curriculares da mesma área científica, e de tornar mais interessante a aquisição de novos conceitos matemáticos.
- Antileishmanial activity of meroditerpenoids from the macroalgae Cystoseira baccataPublication . Sousa, Carolina Bruno de; Gangadhar, Katkam N.; Morais, Thiago R.; Conserva, Geanne A. A.; Vizetto-Duarte, C; Pereira, H.; Laurenti, Marcia D.; Campino, Lenea; Levy, Debora; Uemi, Miriam; Barreira, Luísa; Custódio, L.; Passero, Luiz Felipe D.; Lago, Joao Henrique G.; Varela, JoãoThe development of novel drugs for the treatment of leishmaniases continues to be crucial to overcome the severe impacts of these diseases on human and animal health. Several bioactivities have been described in extracts from macroalgae belonging to the Cystoseira genus. However, none of the studies has reported the chemical compounds responsible for the antileishmanial activity observed upon incubation of the parasite with the aforementioned extracts. Thus, this work aimed to isolate and characterize the molecules present in a hexane extract of Cystoseira baccata that was found to be bioactive against Leishmania infantum in a previous screening effort. A bioactivity-guided fractionation of the C. baccata extract was carried out and the inhibitory potential of the isolated compounds was evaluated via the MIT assay against promastigotes and murine macrophages as well as direct counting against intracellular amastigotes. Moreover, the promastigote ultrastructure, DNA fragmentation and changes in the mitochondrial potential were assessed to unravel their mechanism of action. In this process, two antileishmanial meroditerpenoids, (3R)- and (3S)-tetraprenyltoluquinol (1a/1b) and (3R)- and (3S)-tetraprenyltoluquinone (2a/2b), were isolated. Compounds 1 and 2 inhibited the growth of the L. infantum promastigotes (IC50 = 44.9 +/- 4.3 and 94.4 +/- 10.1 mu M, respectively), inducing cytoplasmic vacuolization and the presence of coiled multilamellar structures in mitochondria as well as an intense disruption of the mitochondrial membrane potential. Compound 1 decreased the intracellular infection index (IC50 = 25.0 +/- 4.1 mu M), while compound 2 eliminated 50% of the intracellular amastigotes at a concentration > 88.0 mu M. This work identified compound 2 as a novel metabolite and compound 1 as a biochemical isolated from Cystoseira algae displaying antileishmanial activity. Compound 1 can thus be an interesting scaffold for the development of novel chemotherapeutic molecules for canine and human visceral leishmaniases studies. This work reinforces the evidence of the marine environment as source of novel molecules. (C) 2017 Elsevier Inc. All rights reserved.
- GACN: Self-clustering genetic algorithm for constrained networksPublication . A. Martins, J.; Mazayev, Andriy; Correia, Noélia; Schutz, G.; Barradas, A.Extending the lifespan of a wireless sensor network is a complex problem that involves several factors, ranging from device hardware capacity (batteries, processing capabilities, and radio efficiency) to the chosen software stack, which is often unaccounted for by the previous approaches. This letter proposes a genetic algorithm-based clustering optimization method for constrained networks that significantly improves the previous state-of-the-art results, while accounting for the specificities of the Internet engineering task force, Constrained RESTful Environment (CoRE), standards for data transmission and specifically relying on CoRE interfaces, which fit this purpose very well.
- 5th International European Turfgrass Society Conference: Crop Science Special IssuePublication . Guerrero, Carlos
- Intelligent non-invasive modeling of ultrasound-induced temperature in tissue phantomsPublication . Ferreira, R.; Ruano, M G; Ruano, AntonioRaising temperature of human cells (hyperthermia) is an ancient tool for tumor masses reduction and extinction, actually even before the existence of a molecular understanding of cancer cells. Hyperthermia is being increasingly used for patients' rehabilitation and oncological diseases' treatment but still constitutes a major driver for researching more efficient and reliable therapeutic usage aiming at outstanding patients wellbeing and socio-economic benefits. Efficient hyperthermia practice demands knowledge about the exact amount of heating required at a particular tissue location, as well as information concerning the spatial heating distribution. Both of these processes require accurate characterization. Until now, ultrasound heating treatments are being monitored by magnetic resonance imaging (MRI), recognized as being capable of achieving a 0.5 degrees C/cm(3) temperature resolution [1], thereby imposing a gold standard in this field. However, one can notice that MRI-based techniques, besides the inconvenient instrumental cost, obliges the presence of a team of expert clinicians and limits the hyperthermia ultrasound treatment area due to the space restrictions of an MRI examination procedure. This article introduces a novel noninvasive modelling approach of ultrasound-induced temperature propagation in tissues, to be used as a cost effective alternative to MRI monitoring of ultrasound therapeutic techniques, achieving a maximum temperature resolution of 0.26 degrees C/cm(3), clearly inferior to the MRI gold standard resolution of 0.5 degrees C/cm(3). In order to derive the model, and avoiding painful invasive in-vivo sampling, a phantom was employed, whose composition respects the human tissues' reaction to ultrasound beams. In contrast with previous works of the authors, in the present paper we study the possibility of using b-spline neural networks (BSNN) as reliable noninvasive estimator of temperature propagation in phantoms [2,3]. The proposed methodology achieves better results than previous approaches, does not require the use of an Imaging Ultrasound transducer and, as the proposed models are piecewise polynomial models, they can be easily inverted and used in closed-loop control of therapeutic ultrasound instruments. (C) 2016 Elsevier Ltd. All rights reserved.
- A regulation-based classification system for marine protected areas: A response to Dudley et al. [9]Publication . Horta e Costa, Bárbara; Claudet, Joachim; Franco, Gustavo; Erzini, Karim; Caro, Anthony; Gonçalves, Emanuel J.Dudley et al. [9] commented on our paper [11], arguing that the current IUCN objective-based categorization of protected areas, which is also used in marine protected areas (MPAs), should not be abandoned and replaced by the new regulation-based classification system [11]. Here we clarify that we do not advocate replacing the current IUCN categories, but highlight the benefits of using both the objective-based IUCN categories and the new regulation-based classification when applied to MPAs. With an increasing number of MPA types being implemented, most of them multiple-use areas zoned for various purposes, assessing ecological and socio-economic benefits is key for advancing conservation targets and policy objectives. Although the IUCN categories can be used both in terrestrial and marine systems, they were not designed to follow a gradient of impacts and there is often a mismatch between stated objectives and implemented regulations. The new regulation-based classification system addresses these problems by linking impacts of activities in marine systems with MPA and zone classes in a simple and globally applicable way. Applying both the IUCN categories and the regulation based classes will increase transparency when assessing marine conservation goals.
- Docosahexaenoic acid loaded lipid nanoparticles with bactericidal activity against Helicobacter pylonPublication . Seabra, Catarina Leal; Nunes, Claudia; Gomez-Lazaro, Maria; Correia, Maria Marta; Machado, José Carlos; Gonçalves, Inês C.; Reis, Celso A.; Reis, Salette; Martins, M. Cristina L.Docosahexaenoic acid (DHA), an omega-3 polyunsaturated fatty acid present in fish oil, has been described as a promising molecule to the treatment of Helicobacter pylori gastric infection. However, due to its highly unsaturated structure, DHA can be easily oxidized loosing part of its bioactivity. This work aims the nanoencapsulation of DHA to improve its bactericidal efficacy against H. pylori. DHA was loaded into nanostructured lipid carriers (NLC) produced by hot homogenization and ultrasonication using a blend of lipids (Precirol AT05 (R), Miglyol-812 (R)) and a surfactant (Tween 60 (R)). Homogeneous NLC with 302 +/- 14 nm diameter,-28 +/- 3 mV surface charge (dynamic and electrophoretic light scattering) and containing 66 +/- 7% DHA (UV/VIS spectroscopy) were successfully produced. Bacterial growth curves, performed over 24 h in the presence of different DHA concentrations (free or loaded into NLC), demonstrated that nanoencapsulation enhanced DHA bactericidal effect, since DHA-loaded NLC were able to inhibit H. pylori growth in a much lower concentrations (25 mu M) than free DHA (>100 mu M). Bioimaging studies, using scanning and transmission electron microscopy and also imaging flow cytometry, demonstrated that DHA-loaded NLC interact with H. pylori membrane, increasing their periplasmic space and disrupting membrane and allowing the leakage of cytoplasmic content. Furthermore, the developed nanoparticles are not cytotoxic to human gastric adenocarcinoma cells at bactericidal concentrations. DHA-loaded NLC should, therefore, be envisaged as an alternative to the current treatments for H. pylori infection. (C) 2017 Elsevier B.V. All rights reserved.
- Diatoms as a paleoproductivity proxy in the NW Iberian coastal upwelling system (NE Atlantic)Publication . Zuniga, Diana; Santos, Célia; Frojan, Maria; Salgueiro, Emilia; Rufino, Marta; De la Granda, Francisco; Figueiras, Francisco G.; Castro, Carmen G.; Abrantes, FatimaThe objective of the current work is to improve our understanding of how water column diatom's abundance and assemblage composition is seasonally transferred from the photic zone to seafloor sediments. To address this, we used a dataset derived from water column, sediment trap and surface sediment samples recovered in the NW Iberian coastal upwelling system. Diatom fluxes (2.2 (+/- 5.6) 10(6) valves m(-2) d(-1)) represented the majority of the siliceous microorganisms sinking out from the photic zone during all studied years and showed seasonal variability. Contrasting results between water column and sediment trap diatom abundances were found during downwelling periods, as shown by the unexpectedly high diatom export signals when diatom- derived primary production achieved their minimum levels. They were principally related to surface sediment remobilization and intense Minho and Douro river discharge that constitute an additional source of particulate matter to the inner continental shelf. In fact, contributions of allochthonous particles to the sinking material were confirmed by the significant increase of both benthic and freshwater diatoms in the sediment trap assemblage. In contrast, we found that most of the living diatom species blooming during highly productive upwelling periods were dissolved during sinking, and only those resistant to dissolution and the Chaetoceros and Leptocylindrus spp. resting spores were susceptible to being exported and buried. Fur-thermore, Chaetoceros spp. dominate during spring-early summer, when persistent northerly winds lead to the upwelling of nutrient-rich waters on the shelf, while Leptocylindrus spp. appear associated with late-summer upwelling relaxation, characterized by water column stratification and nutrient depletion. These findings evidence that the contributions of these diatom genera to the sediment's total marine diatom assemblage should allow for the reconstruction of different past upwelling regimes.
- Approximation in Morrey spacesPublication . Almeida, Alexandre; Samko, StefanA new subspace of Morrey spaces whose elements can be approximated by infinitely differentiable compactly supported functions is introduced. Consequently, we give an explicit description of the closure of the set of such functions in Morrey spaces. A generalisation of known embeddings of Morrey spaces into weighted Lebesgue spaces is also obtained. (C) 2016 Elsevier Inc. All rights reserved.
- Design of remediation pilot plants for the treatment of industrial metal-bearing effluents (BIOMETAL DEMO project): Lab testsPublication . Ballester, Antonio; Castro, Laura; Clara Costa, Maria; Carlier, Jorge; Garcia-Roig, Manuel; Perez-Galende, Patricia; Alvarez, Angela; Bertagnolli, Caroline; Guibal, EricCurrent research is the first part of the BIOMETAL DEMO project, funded by the European Union, focusing on the development of complementary and modular biotreatment processes for the removal of metal ions from industrial effluents (issued from mining industry, surface treatment and ceramics). Metal bio-precipitation (in form of metal sulfides and metal phosphates) using sulfate-reducing bacteria (SRB), phytase and phosphatase enzymes, biosorption using sugar-beet pulp, algal biomass and alginate- or chitosan-based composites (immobilizing polyethyleneimine derivatives by encapsulation) have been extensively studied using synthetic and industrial effluents. These preliminary results allow designing a treatment flow-sheet including pre-treatment of the effluent using biologically-assisted precipitation followed by biosorption (for mining effluents that contain sulfate anions). For surface treatment and ceramics effluents, bio-precipitation combined with biosorption processes and physicochemical pretreatment followed by biosorption process represent, respectively, a promising solution. The carbon-source for the SRB process, the optimization of process parameters and the biosorbents have been selected taking into account both the technical performance and the economic viability. (C) 2016 Elsevier B.V. All rights reserved.