Mostrando recursos 1 - 20 de 1.353

  1. New endoperoxides highly active in vivo and in vitro against artemisinin-resistant Plasmodium falciparum

    Lobo, Lis; Cabral, Lília I. L.; Sena, Maria I.; Guerreiro, Bruno; Rodrigues, António S.; de Andrade-Neto, Valter F.; Cristiano, Maria Lurdes Santos; Nogueira, Fatima
    Background: The emergence and spread of Plasmodium falciparum resistance to artemisinin-based combination therapy in Southeast Asia prompted the need to develop new endoperoxide-type drugs. Methods: A chemically diverse library of endoperoxides was designed and synthesized. The compounds were screened for in vitro and in vivo anti-malarial activity using, respectively, the SYBR Green I assay and a mouse model. Ring survival and mature stage survival assays were performed against artemisinin-resistant and artemisinin-sensitive P. falciparum strains. Cytotoxicity was evaluated against mammalian cell lines V79 and HepG2, using the MTT assay. Results: The synthesis and anti-malarial...

  2. Novel triblock co-polymer nanofibre system as an alternative support for embryonic stem cells growth and pluripotency

    Perestrelo, Ana Rubina; Mouffouk, Fouzi; Costa, Ana M. Rosa da; Belo, José
    Conventionally, embryonic stem cells (ESCs) are cultured on gelatin or over a mitotically inactivated monolayer of mouse embryonic fibroblasts (MEFsi). Considering the lack of versatile, non-animal-derived and inexpensive materials for that purpose, we aimed to find a biomaterial able to support ESC growth in a pluripotent state that avoids the need for laborious and time-consuming MEFsi culture in parallel with mouse ESC (mESC) culture. Undifferentiated mESCs were cultured in a new nanofibre material designed for ESC culture, which is based on the self-assembly of a triblock copolymer, poly(ethyleneglycol-beta-trimethylsilyl methacrylate-beta-methacrylic acid), conjugated with the peptide glycine-arginine-glycine-aspartate-serine, to evaluate its potential application...

  3. Performance and bacterial community shifts during phosphogypsum biotransformation

    Martins, Mónica; Assunção, Ana; Neto, André; Silva, Gonçalo; Sghaier, Haitham; Costa, Maria Clara
    Phosphogypsum (PG) is an industrial waste composed mainly by sulfate, turning it a suitable sulfate source for sulfate-reducing bacteria (SRB). In the present work, the capability of two SRB communities, one enriched from Portuguese PG (culture PG) and the other from sludge from a wastewater treatment plant (culture WWT-1), to use sulfate from PG was compared. In addition, the impact of this sulfate-rich waste in the microbial community was assessed. The highest efficiency in terms of sulfate reduction was observed with culture WWT-1. The bacterial composition of this culture was not significantly affected when sodium sulfate from the nutrient medium...

  4. Temporal metabolic profiling of theQuercus suber-Phytophthora cinnamomisystem by middle-infrared spectroscopy

    Hardoim, P. R.; Guerra, Rui; Costa, Ana M. Rosa da; Serrano, M. S.; Sánchez, M. E.; Coelho, A. C.
    The oomycete Phytophthora cinnamomi is an aggressive plant pathogen, detrimental to many ecosystems including cork oak (Quercus suber) stands, and can inflict great losses in one of the greatest ‘hotspots’ for biodiversity in the world. Here, we applied Fourier transform-infrared (FT-IR) spectroscopy combined with chemometrics to disclose the metabolic patterns of cork oak roots and P. cinnamomi mycelium during the early hours of the interaction. As early as 2 h post-inoculation (hpi), cork oak roots showed altered metabolic patterns with significant variations for regions associated with carbohydrate, glycoconjugate and lipid groups when compared to mockinoculated plants. These variations were further extended...

  5. Novel triblock co-polymer nanofibre system as an alternative support for embryonic stem cells growth and pluripotency

    Perestrelo, Ana Rubina; Mouffouk, Fouzi; Costa, Ana M. Rosa da; Belo, José
    Conventionally, embryonic stem cells (ESCs) are cultured on gelatin or over a mitotically inactivated monolayer of mouse embryonic fibroblasts (MEFsi). Considering the lack of versatile, non-animal-derived and inexpensive materials for that purpose, we aimed to find a biomaterial able to support ESC growth in a pluripotent state that avoids the need for laborious and time-consuming MEFsi culture in parallel with mouse ESC (mESC) culture. Undifferentiated mESCs were cultured in a new nanofibre material designed for ESC culture, which is based on the self-assembly of a triblock co-polymer, poly(ethyleneglycol-β-trimethylsilyl methacrylate-β-methacrylic acid), conjugated with the peptide glycine-arginine-glycine-aspartate-serine, to evaluate its potential application...

  6. Recovery of gold(0) nanoparticles from aqueous solutions using effluents from a bioremediation process

    Assunção, Ana; Vieira, Bernardete; Lourenço, J. P.; Costa, Maria Clara
    The use of biological processes with the aim of the recovery of gold from low-concentration solutions derived from leaching of secondary sources is gaining increasing importance owing to the scarcity of the primary resources and the economic and environmental advantages usually presented by these methods. Thus, the addition in batch and continuous processes of different solutions containing biogenic sulphide, which was generated by the activity of sulphate-reducing bacteria (SRB), to gold(III) solutions was investigated for that purpose. In the batch experiments, AuS nanoparticles with sizes of between 6 and 14 nm were obtained (corresponding to 100% removal of Au(III) from...

  7. Application of urea-agarose gel electrophoresis to select non-redundant 16S rRNAs for taxonomic studies: palladium(II) removal bacteria

    Assunção, Ana; Costa, Maria Clara; Carlier, Jorge Dias
    The 16S ribosomal RNA (rRNA) gene has been the most commonly used sequence to characterize bacterial communities. The classical approach to obtain gene sequences to study bacterial diversity implies cloning amplicons, selecting clones, and Sanger sequencing cloned fragments. A more recent approach is direct sequencing of millions of genes using massive parallel technologies, allowing a large-scale biodiversity analysis of many samples simultaneously. However, currently, this technique is still expensive when applied to few samples; therefore, the classical approach is still used. Recently, we found a community able to remove 50 mg/L Pd(II). In this work, aiming to identify the bacteria...

  8. A bridge between liquid-liquid extraction and the use of bacterial communities for palladium and platinum recovery as nanosized metal sulphides

    Assunção, Ana; Matos, Ana; Costa, Ana M. Rosa da; Candeias, Antonio; Costa, Maria Clara
    The Platinum Group Metals (PGM) are rare in the Earth's crust and in the past years their use had a considerable expansion limiting their availability, which justifies PGM's high commercial value and demand. Therefore, PGM recovery from secondary sources is very important from both economic and environmental points of view. In recent years, several methods for PGM removal have been investigated. Our research group has been studying the removal/recovery of PGM using both chemical (liquid liquid extraction) and biological methods (using anaerobic bacterial communities).The aim of this study was to combine these two chemical and biological approach technologies, for PGM...

  9. The Widely scalable Mobile Underwater Sonar Technology (WiMUST) H2020 project: first year status

    Antonelli, Gianluca; Caffaz, Andrea; Casalino, Giuseppe; Volpi, Nicola Catenacci; de Jong, Ivan Bielic; De Palma, Daniela; Duarte, Henrique; Grimsdale, Jonathan; Indiveri, Giovanni; Jesus, S. M.; Kebkal, Konstantin; Pascoal, Antonio; Polani, Daniel; Pollini, Lorenzo
    The Widely scalable Mobile Underwater Sonar Technology (WiMUST) project aims at developing a system of cooperative Autonomous Underwater Vehicles (AUVs) for geotechnical surveying and geophysical exploration. The paper reports about the first year activities and it gives an overview of the main objectives and methods. Results relative to distributed sensor array, cooperative control, mission planning, communications and preliminary experiments are summarized.

  10. Close range ship noise cross correlations with a vector sensor in view of geoacoustic inversion

    Wu Yanqun; Santos, Ana Bela; Felisberto, Paulo; Jesus, S. M.
    Distant ship noise has been utilized for geoacoustic inversion and ocean monitoring for many years. In a shallow water experiment, Makai 2005, a 4-element acoustic vector sensor array was deployed at the stern of the research vessel R/V Kilo Moana. The recorded engine noise of R/V Kilo Moana during its dynamic positioning was analyzed by the DEMON (Detection of Envelope Modulation on Noise) method. The strongest modulation frequency band of the ship noise was found by a group of band-pass filters for further data processing. Multipath arrivals in the vertical particle velocity have higher signal-to-noise ratios than those in the...

  11. Acoustic Channel Frequency Response Estimation Using Sources of Opportunity

    Santos, Ana Bela; Felisberto, P.; Jesus, S. M.
    This work addresses the usage of ship radiated noise to estimate the ocean acoustic water propagation channel response between two vertical line arrays. We derive an expression for the frequency response channel estimate using a normal mode development based on cross-correlation methods, in a similar way as Roux et al. [1]. Its applicability and limitations in simulated and real conditions is discussed. Simulations are conducted using the normal mode model KRAKEN, based on the experimental setup and environmental parameters gathered during the RADAR' 07 sea trial, off the west coast of Portugal, in July of 2007. In this sea trial...

  12. Distributed sensor array for bottom inversion

    Jesus, S. M.
    Seismic inversion with an AUV-based sensor array system is an appealing concept that opens up a number of interesting possibilities but faces also a number of technological and scientific challenges. Among the technological challenges there is the fact that sensor arrays are no longer hardwired to the tow ship and therefore on the fly data monitoring imposes stringent restrictions on the amount of data that can be sent to the support ship. One of the scientific challenges is to determine the optimal sensor array configuration by exploring AUV mobility for inverting the bottom geophysical structure of interest. In fact, the...

  13. A criterion for reflectiveness of normal extensions

    Montoli, Andrea; Rodelo, Diana; Van der Linden, Tim
    We give a new sufficient condition for the normal extensions in an admissible Galois structure to be reflective. We then show that this condition is indeed fulfilled when X is the (protomodular) reflective subcategory of S-special objects of a Barr-exact S-protomodular category C, where S is the class of split epimorphic trivial extensions in C. Next to some concrete examples where the criterion may be applied, we also study the adjunction between a Barr-exact unital category and its abelian core, which we prove to be admissible.

  14. Higher central extensions and cohomology

    Rodelo, Diana; Van der Linden, Tim
    We establish a Galois-theoretic interpretation of cohomology in semi-abelian categories: cohomology with trivial coefficients classifies central extensions, also in arbitrarily high degrees. This allows us to obtain a duality, in a certain sense, between "internal" homology and "external" cohomology in semiabelian categories. These results depend on a geometric viewpoint of the concept of a higher central extension, as well as the algebraic one in terms of commutators. (C) 2015 Elsevier Inc. All rights reserved.

  15. Widely scalable mobile underwater sonar technology: an overview of the H2020 WiMUST project

    Abreu, Pedro; Antonelli, Gianluca; Arrichiello, Filippo; Caffaz, Andrea; Caiti, Andrea; Casalino, Giuseppe; Volpi, Nicola Catenacci; de Jong, Ivan Bielic; De Palma, Daniela; Duarte, Henrique; Gomes, Joao Pedro; Grimsdale, Jonathan; Indiveri, Giovanni; Jesus, S. M.; Kebkal, Konstantin; Kelholt, Elbert; Pascoal, Antonio; Polani, Daniel; Pollini, Lorenzo; Simetti, Enrico; Turetta, Alessio
    The Widely scalable Mobile Underwater Sonar Technology (WIMUST) project is an H2020 Research and Innovation Action funded by European Commission. The project aims at developing a system of cooperative autonomous underwater vehicles (AUVs) for geotechnical surveying and geophysical exploration. The paper describes the main objectives of the project, given an overview of the methodologies adopted to achieve them, and summarizes the work done in the first year of R&D work.

  16. Direction-finding arrays of directional sensors for randomly located sources

    Gazzah, Houcem; Delmas, Jean Pierre; Jesus, S. M.
    The problem of directional sensor placement and orientation is considered when statistical information about the source direction of arrival is available. We focus on two-sensor arrays and form a cost function based on the Cramer-Rao bound that depends on the probability distribution of the coplanar source direction. Proper positioning and orientation of the sensors enable the two-sensor array to have an accuracy comparable to that of a three-or four-sensor uniform circular array.

  17. MERIS phytoplankton time series products from the SW Iberian Peninsula (Sagres) using seasonal-trend decomposition based on loess

    Cristina, Sónia; Cordeiro, Clara; Lavender, Samantha; Goela, Priscila; Icely, John; Newton, Alice
    The European Space Agency has acquired 10 years of data on the temporal and spatial distribution of phytoplankton biomass from the MEdium Resolution Imaging Spectrometer (MERIS) sensor for ocean color. The phytoplankton biomass was estimated with the MERIS product Algal Pigment Index 1 (API 1). Seasonal-Trend decomposition of time series based on Loess (STL) identified the temporal variability of the dynamical features in the MERIS products for water leaving reflectance ((w)()) and API 1. The advantages of STL is that it can identify seasonal components changing over time, it is responsive to nonlinear trends, and it is robust in the...

  18. Technical note: Algal Pigment Index 2 in the Atlantic off the southwest Iberian Peninsula: standard and regional algorithms

    Goela, Priscila; Cristina, Sonia; Kajiyama, Tamito; Icely, John; Moore, Gerald; Fragoso, Bruno; Newton, Alice
    In this study, Algal Pigment Index 2 (API2) is investigated in Sagres, an area located in the Atlantic off the southwestern Iberian Peninsula. Standard results provided by the MEdium Resolution Image Spectrometer (MERIS) ocean colour sensor were compared with alternative data products, determined through a regional inversion scheme, using both MERIS and in situ remote sensing reflectances (R-rs) as input data. The reference quantity for performance assessment is in situ total chlorophyll a (TChl a) concentration estimated through a phytoplankton absorption coefficient (i.e. equivalent to API2). Additional comparison of data products has also been addressed for TChl a concentration determined...

  19. Global analysis of seagrass restoration: the importance of large-scale planting

    van Katwijk, Marieke M.; Thorhaug, Anitra; Marba, Nuria; Orth, Robert J.; Duarte, Carlos M.; Kendrick, Gary A.; Althuizen, Inge H. J.; Balestri, Elena; Bernard, Guillaume; Cambridge, Marion L.; Cunha, Alexandra; Durance, Cynthia; Giesen, Wim; Han, Qiuying; Hosokawa, Shinya; Kiswara, Wawan; Komatsu, Teruhisa; Lardicci, Claudio; Lee, Kun-Seop; Meinesz, Alexandre; Nakaoka, Masahiro; O'Brien, Katherine R.; Paling, Erik I.; Pickerell, Chris; Ransijn, Aryan M. A.; Verduin, Jennifer J.
    In coastal and estuarine systems, foundation species like seagrasses, mangroves, saltmarshes or corals provide important ecosystem services. Seagrasses are globally declining and their reintroduction has been shown to restore ecosystem functions. However, seagrass restoration is often challenging, given the dynamic and stressful environment that seagrasses often grow in. From our world-wide meta-analysis of seagrass restoration trials (1786 trials), we describe general features and best practice for seagrass restoration. We confirm that removal of threats is important prior to replanting. Reduced water quality (mainly eutrophication), and construction activities led to poorer restoration success than, for instance, dredging, local direct impact and...

  20. International Centre for Coastal Ecohydrology: applying the ecohydrology approach for the sustainable functioning of coastal ecosystems

    Chícharo, L.; Ben-Hamadou, R.; Amaral, A.; Range, P.; Mateus, C.; Piló, D.; Marques, R.; Morais, P.; Chícharo, M. A.
    Coastal areas are among the most sensitive and productive ecosystems around the world, providing for the subsistence of large numbers of people, particularly in developing countries. Human pressure on coastal areas has dramatically increased during the last decades and climate changes will pose new threats to these areas, as expected from sea-level rise and the decrease in freshwater discharges from rivers (Chicharo et al., 2009). The International Centre for Coastal Ecohydrology (ICCE) a newly approved centre under the auspices of UNESCO, in October 2009, is located in the Algarve region (south Portugal). The centre acts as a facilitator and synergetic structure by providing the articulation...

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