University Of Lisboalisboa


University Of Lisboalisboa

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Guerreiro B.J.,University of Macau | Guerreiro B.J.,University of Lisbon | Silvestre C.,University of Macau | Silvestre C.,University Of Lisboalisboa | Cunha R.,University of Lisbon
Advances in Intelligent Systems and Computing | Year: 2016

This paper addresses the problem of trajectory tracking control of autonomous rotorcraft relative to pole-shaped structures using LiDAR sensors. The proposed approach defines an alternative kinematic model, directly based on LiDAR measurements, and uses a trajectory-dependent error space to express the dynamic model of the vehicle. An LPV representation with piecewise affine dependence on the parameters is adopted to describe the error dynamics over a set of predefined operating regions. The synthesis problem is stated as a continuous-time H2 control problem, solved using LMIs and implemented within the scope of gain-scheduling control theory. The performance of the proposed control method is validated with comprehensive simulation results. © Springer International Publishing Switzerland 2016.

Heinola K.,University of Helsinki | Heinola K.,EURATOM | Widdowson A.,EURATOM | Likonen J.,Tekes | And 10 more authors.
Journal of Nuclear Materials | Year: 2015

Abstract Selected Ion Beam Analysis techniques applicable for detecting deuterium and heavier impurities have been used in the post-mortem analyses of tiles removed after the first JET ITER-Like Wall (JET-ILW) campaign. Over half of the retained fuel was measured in the divertor region. The highest figures for fuel retention were obtained from regions with the thickest deposited layers, i.e. in the inner divertor on top of tile 1 and on the High Field Gap Closure tile, which resides deep in the plasma scrape-off layer. Least retention was found in the main chamber high erosion regions, i.e. in the mid-plane of Inner Wall Guard Limiter. The fuel retention values found typically varied with deposition layer thicknesses. The reported retention values support the observed decrease in fuel retention obtained with gas balance experiments of JET-ILW. © 2015 EURATOM.

PubMed | Institute Investigacao e Inovacao em Saude Porto, University Of Lisboalisboa, University of Lisbon and SA Cantanhede
Type: | Journal: Frontiers in microbiology | Year: 2016

Blad polypeptide comprises residues 109-281 of

PubMed | University Of Lisboalisboa and University of Lisbon
Type: | Journal: Frontiers in plant science | Year: 2016

Subtilisin-like proteases, also known as subtilases, are a very diverse family of serine peptidases present in many organisms. In grapevine, there are hints of the involvement of subtilases in defense mechanisms, but their role is not yet understood. The first characterization of the subtilase gene family was performed in 2014. However, simultaneously, the grapevine genome was re-annotated and several sequences were re-annotated or retrieved. We have performed a re-characterization of this family in grapevine and identified 82 genes coding for 97 putative proteins, as result of alternative splicing. All the subtilases identified present the characteristic S8 peptidase domain and the majority of them also have a pro-domain I9 inhibitor, a protease-associated (PA) domain, and a signal peptide for targeting to the secretory pathway. Phylogenetic studies revealed six subtilase groups denominated

PubMed | University Of Lisboalisboa and University of Lisbon
Type: | Journal: Frontiers in chemistry | Year: 2016

Water is the major component of cells and tissues throughout all forms of life. Fluxes of water and solutes through cell membranes and epithelia are essential for osmoregulation and energy homeostasis. Aquaporins are membrane channels expressed in almost every organism and involved in the bidirectional transfer of water and small solutes across cell membranes. Aquaporins have important biological roles and have been implicated in several pathophysiological conditions suggesting a great translational potential in aquaporin-based diagnostics and therapeutics. Detecting aquaporin function is critical for assessing regulation and screening for new activity modulators that can prompt the development of efficient medicines. Appropriate methods for functional analysis comprising suitable cell models and techniques to accurately evaluate water and solute membrane permeability are essential to validate aquaporin function and assess short-term regulation. The present review describes established assays commonly used to assess aquaporin function in cells and tissues, as well as the experimental biophysical strategies required to reveal functional regulation and identify modulators, the first step for aquaporin drug discovery.

Cartaxo M.A.M.,Polytechnic Institute of Tomar | Cartaxo M.A.M.,University Of Lisboalisboa | Borges C.M.,University Of Lisboalisboa | Pereira M.I.S.,University Of Lisboalisboa | Mendonca M.H.,University Of Lisboalisboa
Electrochimica Acta | Year: 2015

Abstract Steel, Pt and pelleted Co2FeO4 electrodes were used for the electrochemical oxidation of paraquat in aqueous solutions at room temperature. The oxide electrodes were characterized by cyclic voltammetry. Paraquat electrochemical oxidation was carried out by electrolysis at constant current and monitored by UV-vis absorbance measurements. Different anode/cathode pairs were used. After 1.5 h of electrolysis the highest removal (≈79%), was obtained with the electrode pair Pt/steel followed by Co2FeO4/Pt (≈55%), corresponding to the paraquat oxidation by a conversion mechanism. Removals of ≈64% were obtained with Co2FeO4 / Co2FeO4 after 3 h of electrolysis. Mass spectrometry analysis indicates that the main intermediate oxidation products were monopyridone and dipyridone derivatives. © 2015 Elsevier Ltd.

Shimizu K.,University Of Lisboalisboa | Canongia Lopes J.N.,University Of Lisboalisboa | Canongia Lopes J.N.,New University of Lisbon | Goncalves Da Silva A.M.P.S.,University Of Lisboalisboa
Langmuir | Year: 2015

The behavior of ionic liquids trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide and trihexyl(tetradecyl)phosphonium dicyanamide, [P6 6 6 14][Ntf2] and [P6 6 6 14][N(CN)2], respectively, at the water-air interface was investigated using the Langmuir trough technique. The obtained surface pressure versus mean molecular area (MMA) isotherms, π-A, and surface potential versus MMA isotherms, ΔV-A, show distinct interfacial behavior between the two systems. The results were interpreted at a molecular level using molecular dynamics simulations: the different compression regimes along the [P6 6 6 14][Ntf2] isotherm correspond to the self-organization of the ions at the water surface into compact and planar monolayers that coalesce at an MMA value of ca. 1.85 nm2/ion pair to form an expanded liquidlike layer. Upon further compression, the monolayer collapses at around 1.2 nm2/ion pair to yield a progressively thicker and less organized layer. These transitions are much more subdued in the [P6 6 6 14][N(CN)2] system because of the more hydrophilic nature of the dicyanamide anion. The numerical density profiles obtained from the MD simulation trajectories are also able to emphasize the very unusual packing of the four long alkyl side chains of the cation above and below the ionic layer that forms at the water surface. Such a distribution is also different for the two studied systems during the different compression regimes. © 2015 American Chemical Society.

Costa F.F.,University Of Lisboalisboa | Costa M.,University Of Lisboalisboa
Fuel | Year: 2015

Abstract Particle fragmentation corresponds to the particle disintegration during combustion, yielding two or more particles of smaller size. Torrefaction consists in exposing biomass to an inert atmosphere between 260 °C and 300 °C. In such conditions, hemicellulose is partially decomposed allowing some low calorific volatiles to be released from the raw biomass, thus enhancing the biomass energetic potential. From this process, it is possible to obtain a new material whose properties range between biomass and coal. However, one of the torrefied biomass characteristics consists in its brittle nature, and, thus, more prone and easily breakable in milling processes. This study aims to understand if and how torrefaction promotes particle fragmentation during biomass combustion. Initially, pine shells, olive stones and wheat straw were torrefied at 280 °C. Subsequently, all biomass fuels, both raw and torrefied, were burnt in a drop tube furnace (DTF) at 1100 °C. The results reported include profiles of temperature, particle burnout and PM concentrations and size distributions measured along the DTF. In addition, particles of the raw biomass fuels and PM collected for all biomass fuels from two DTF axial positions were examined in a scanning electron microscope. The data reveal that (i) pine shells present the lowest PM concentrations due to its lower ash content and highest burnout values; (ii) particle fragmentation does not occur during the combustion of raw and torrefied olive stones; (iii) particle fragmentation occurs during the combustion of raw and torrefied pine shells and wheat straw, but torrefaction promotes particle fragmentation only in the case of the straw. © 2015 Elsevier Ltd.

Lucas C.,University Of Lisboalisboa | Guedes Soares C.,University Of Lisboalisboa
Ocean Engineering | Year: 2015

Abstract This work presents the results of the fit of three bivariate models to twelve years of significant wave height and mean zero-crossing period data of swell, wind sea components, and combined sea states from Australia. The Conditional Modelling Approach defines the joint distribution from a marginal distribution of significant wave height and a set of distributions of mean zero-crossing period conditional on significant wave height. The second model fits the Plackett model to the data, and the last one applies the Box-Cox transformations to the data with the aim of making it approximately normal to fit a bivariate normal distribution to the transformed data. The conditional model with a lognormal distribution for the significant wave height and lognormal distributions for the zero-crossing period gave the best fit for the total sea states and for the wind component. In case of the swell component the conditional model with a Weibull distribution to the significant wave height and a lognormal distribution to the mean zero-crossing period gave a relatively close fit to the data. © 2015 Elsevier Ltd.

Neves A.,University Of Lisboalisboa | Sequeira V.,University Of Lisboalisboa | Vieira A.R.,University Of Lisboalisboa | Paiva R.B.,University Of Lisboalisboa | Gordo L.S.,University Of Lisboalisboa
Acta Ichthyologica et Piscatoria | Year: 2015

Background. The small red scorpionfish, Scorpaena notata Rafinesque, 1810, appears as a bycatch of Portuguese fisheries. Bycatch species are likely to suffer the same declines as commercial species with which they co-occur but information on those species for Portuguese waters does not exist. In order to increase the knowledge for the Portuguese continental-shelf waters several aspects of the species growth were investigated. Materials and methods. Age and growth of Scorpaena notata from Portuguese continental-shelf waters were studied using 379 otoliths. A subsample of 70 otoliths, covering all length classes, was read by three of the authors to establish a reading and interpretation pattern. The von Bertalanffy growth model was fitted to sex-specific age-length data. The likelihood ratio tests were used to evaluate the significance of differences on growth parameters between sexes and with the parameters estimated in different areas. Results. Females dominated in smaller length classes while males prevailed in larger ones, although overall sex ratio did not deviate from 1 : 1. Females ranged from 10.5 to 18.8 cm total length (TL) and from 1 to 6 years; males ranged from 11.4 to 20.7 cm TL and from 1 to 7 years. The von Bertalanffy growth parameters estimated for the Portuguese shelf waters showed significant differences between sexes and were: L= 18.23 cm TL, k = 0.43yr-1, t0 = -0.99 yr for females and L= 21.17 cm TL, k = 0.28yr-1and t0 = -1.73 yr for males. The age range found in the Portuguese shelf waters was similar to that found in the Balearic Islands but about half of that found for the Adriatic Sea. Significant differences between growth parameters from the Portuguese coast and those from the Balearic Islands and Adriatic Sea were found. Conclusion. Estimates of Lin the presently reported study were the highest but rather consistent with the maximum length given for the species. © 2015, Scientific Society of Szczecin. All rights reserved.

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