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2015
Vicente, António, Hugo Águas, Tiago Mateus, Andreia Araújo, Andriy Lyubchyk, Simo Siitonen, Elvira Fortunato, and Rodrigo Martins. "Solar cells for self-sustainable intelligent packaging." Journal of Materials Chemistry A. 3 (2015): 13226-13236. Abstract
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Neagu, E. R., M. C. Lanca, C. J. Dias, and J. N. Marat-Mendes. "Space Charge and Dipolar Charge Contribution at Polar Polymers Polarization." Ieee Transactions on Dielectrics and Electrical Insulation. 22 (2015): 1419-1426. AbstractWebsite
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Tschopp, Emanuel, Octávio Mateus, and Roger B. J. Benson. "A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda)." {PeerJ}. 3 (2015): e857. AbstractWebsite
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Marques, Filipe J., and Carlos A. Coelho. "The sphericity versus equivariance-equicorrelation test." AIP Conference Proceedings. Vol. 1648. AIP Publishing, 2015. 540009. Abstract
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Polcyn, {M. J. }, LL Jacobs, AS Schulp, and O. Mateus Tethyan and Weddellian biogeographic mixing in the Maastrichtian of Angola. Journal of Vertebrate Paleontology, 2015. Abstract
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Águas, Hugo, Tiago Mateus, António Vicente, Diana Gaspar, Manuel J. Mendes, Wolfgang A. Schmidt, Lu{\'ıs Pereira, Elvira Fortunato, and Rodrigo Martins. "Thin film silicon photovoltaic cells on paper for flexible indoor applications." Advanced Functional Materials. 25 (2015): 3592-3598. Abstract
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Polcyn, {Michael J. }, {Louis L. } Jacobs, {Anne S. } Schulp, and Octávio Mateus Trolling the Cretaceous Seas: Marine Amniotes of Two West Coast Margins. Geological Society of America Abstracts with Programs. Vol. 47, No. 4, p.55, 2015. Abstract

In this session we review the Upper Cretaceous marine amniote records from the west coasts of North America and Africa. Recent work by our group in Angola, on the west coast of Africa, has opened up new fossiliferous localities, producing well-preserved turtles, plesiosaurs, and mosasaurs, ranging in age from Late Turonian to Late Maastrichtian. These African localities were deposited in arid latitudes and highly productive upwelling zones along the passive margin of a growing South Atlantic Ocean. The fossil record of Cretaceous marine amniotes from the West Coast of North America is relatively meager when compared to the African record and the prolific fossil beds laid down in the epicontinental seas of the Western Interior Seaway and northern Europe. Nonetheless, these localities provide an important glimpse of a marine ecosystem that developed on the active margins of a deep ocean basin. Historically considered to be depauperate and endemic, the west coast fauna was characterized by unusual forms such as Plotosaurus, arguably one of the most derived mosasaurs; however, in recent years, additional taxa have been described, revealing species diversity and ecological partitioning within these communities and in some cases, faunal interchange with other regions. The large quantity of well-preserved fossils from the west coast of Africa is influenced in part by its paleogeographic position, deposited within highly productive areas of Hadley Cell controlled upwelling zones. By contrast, the North American west coast localities have been deposited in temperate and higher latitudes since the Late Cretaceous. Nonetheless, the North American and African faunas share some common characteristics in a possessing a mix of endemic and more cosmopolitan forms. Habitat partitioning reflected in tooth form and body size is comparable between the Angolan and the North American west coast, and there is remarkable convergence in taxa which appear to exploit certain like-niches.

Silva, Tiago A. N., A. Carvalho, Nuno M. M. Maia, and John E. Mottershead Uncertainty quantification by fuzzifying an experimental data set. ICEDyn2015 - International Conference on Structural Engineering Dynamics. Lagos, 2015. Abstract
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Palma, A. S., Y. Liu, H. Zhang, Y. Zhang, B. V. McCleary, G. Yu, Q. Huang, L. S. Guidolin, A. E. Ciocchini, A. Torosantucci, D. Wang, AL Carvalho, C. M. Fontes, B. Mulloy, R. A. Childs, T. Feizi, and W. Chai. "Unravelling glucan recognition systems by glycome microarrays using the designer approach and mass spectrometry." Mol Cell Proteomics (2015). AbstractWebsite

Glucans are polymers of D-glucose with differing linkages in linear or branched sequences. They are constituents of microbial and plant cell-walls and involved in important bio-recognition processes including immunomodulation, anti-cancer activities, pathogen virulence and plant cell-wall biodegradation. Translational possibilities for these activities in medicine and biotechnology are considerable. High-throughput micro-methods are needed to screen proteins for recognition of specific glucan sequences as a lead to structure-function studies and their exploitation. We describe construction of a glucome microarray, the first sequence-defined glycome-scale microarray, using a designer approach from targeted ligand-bearing glucans in conjunction with a novel high-sensitivity mass spectrometric sequencing method, as a screening tool to assign glucan recognition motifs. The glucome microarray comprises 153 oligosaccharide probes with high purity, representing major sequences in glucans. The negative-ion electrospray tandem mass spectrometry with collision-induced dissociation was used for complete linkage analysis of gluco-oligosaccharides in linear homo and hetero and branched sequences. The system is validated using antibodies and carbohydrate-binding modules known to target α- or β-glucans in different biological contexts, extending knowledge on their specificities, and applied to reveal new information on glucan recognition by two signalling molecules of the immune system against pathogens: Dectin-1 and DC-SIGN. The sequencing of the glucan oligosaccharides by the MS method and their interrogation on the microarrays provides detailed information on linkage, sequence and chain length requirements of glucan-recognizing proteins, and are a sensitive means of revealing unsuspected sequences in the polysaccharides.

Palma, Angelina S., Yan Liu, Hongtao Zhang, Yibing Zhang, Barry V. McCleary, Guangli Yu, Qilin Huang, Leticia S. Guidolin, Andres E. Ciocchini, Antonella Torosantucci, Denong Wang, Ana Luisa Carvalho, Carlos M. G. A. Fontes, Barbara Mulloy, Robert A. Childs, Ten Feizi, and Wengang Chai. "Unravelling Glucan Recognition Systems by Glycome Microarrays Using the Designer Approach and Mass Spectrometry." Molecular & Cellular Proteomics. 14 (2015): 974-988. Abstract
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Barbosa, A. R. a, A. a Lopes, R. a Monteiro, and F. b Castro. "Use of different inorganic solid wastes to produce glass foams." Wastes: Solutions, Treatments and Opportunities - Selected Papers from the 3rd Edition of the International Conference on Wastes: Solutions, Treatments and Opportunities, 2015. 2015. 25-30. Abstract

Cathode Ray Tube (CRT) waste glasses produced from dismantling TV sets were used to prepare glass foams by a simple and economic processing route, consisting of a direct sintering process of mixtures of CRT waste as glass powder with different foaming agents (coal fly ash and limestone quarrying residues). The influence of firing temperature, amount and type of foaming agent on the apparent density, pore size distribution and compressive strength have been studied. The aim of the work was to investigate the possibility to obtain glass foams using exclusively wastes as starting materials, and therefore replacing the conventional raw materials. © 2015 Taylor & Francis Group, London.

Clemmensen, Lars B., Jesper Milàn, Jan Schulz Adolfssen, Eliza Jarl Estrup, Nicolai Frobøse, Nicole Klein, Octávio Mateus, and Oliver Wings. "The vertebrate-bearing Late Triassic Fleming Fjord Formation of central East Greenland revisited: stratigraphy, palaeoclimate and new palaeontological data." Geological Society, London, Special Publications. 434 (2015). AbstractWebsite

In Late Triassic (Norian–Rhaetian) times, the Jameson Land Basin lay at 40° N on the northern part of the supercontinent Pangaea. This position placed the basin in a transition zone between the relatively dry interior of the supercontinent and its more humid periphery. Sedimentation in the Jameson Land Basin took place in a lake–mudflat system and was controlled by orbitally forced variations in precipitation. Vertebrate fossils have consistently been found in these lake deposits (Fleming Fjord Formation), and include fishes, dinosaurs, amphibians, turtles, aetosaurs and pterosaurs. Furthermore, the fauna includes mammaliaform teeth and skeletal material. New vertebrate fossils were found during a joint vertebrate palaeontological and sedimentological expedition to Jameson Land in 2012. These new finds include phytosaurs, a second stem testudinatan specimen and new material of sauropodomorph dinosaurs, including osteologically immature individuals. Phytosaurs are a group of predators common in the Late Triassic, but previously unreported from Greenland. The finding includes well-preserved partial skeletons that show the occurrence of four individuals of three size classes. The new finds support a late Norian–early Rhaetian age for the Fleming Fjord Formation, and add new information on the palaeogeographical and palaeolatitudinal distribution of Late Triassic faunal provinces.

Barros, Alexandre A., A. N. A. Rita, A. R. C. Duarte, Ricardo A. Pires, Belém Sampaio-Marques, Paula Ludovico, Estevão Lima, João F. Mano, and Rui L. Reis. "{Bioresorbable ureteral stents from natural origin polymers}." Journal of Biomedical Materials Research - Part B Applied Biomaterials. 103 (2015): 608-617. Abstract

In this work, stents were produced from natural origin polysaccharides. Alginate, gellan gum, and a blend of these with gelatin were used to produce hollow tube (stents) following a combination of templated gelation and critical point carbon dioxide drying. Morphological analysis of the surface of the stents was carried out by scanning electron microscopy. Indwelling time, encrustation, and stability of the stents in artificial urine solution was carried out up to 60 days of immersion. In vitro studies carried out with simulated urine demonstrated that the tubes present a high fluid uptake ability, about 1000{%}. Despite this, the materials are able to maintain their shape and do not present an extensive swelling behavior. The bioresorption profile was observed to be highly dependent on the composition of the stent and it can be tuned. Complete dissolution of the materials may occur between 14 and 60 days. Additionally, no encrustation was observed within the tested timeframe. The ability to resist bacterial adherence was evaluated with Gram-positive Staphylococcus aureus and two Gram-negatives Escherichia coli DH5 alpha and Klebsiella oxytoca. For K. oxytoca, no differences were observed in comparison with a commercial stent (Biosoft((R)) duo, Porges), although, for S. aureus all tested compositions had a higher inhibition of bacterial adhesion compared to the commercial stents. In case of E. coli, the addition of gelatin to the formulations reduced the bacterial adhesion in a highly significant manner compared to the commercial stents. The stents produced by the developed technology fulfill the requirements for ureteral stents and will contribute in the development of biocompatible and bioresorbable urinary stents.

Mendes, MJ, S. Morawiec, T. Mateus, A. Lyubchyk, H. Águas, I. Ferreira, E. Fortunato, R. Martins, F. Priolo, and I. Crupi. "{Broadband light trapping in thin film solar cells with self-organized plasmonic nanocolloids}." Nanotechnology. 26 (2015). Abstract

© 2015 IOP Publishing Ltd. The intense light scattered from metal nanoparticles sustaining surface plasmons makes them attractive for light trapping in photovoltaic applications. However, a strong resonant response from nanoparticle ensembles can only be obtained if the particles have monodisperse physical properties. Presently, the chemical synthesis of colloidal nanoparticles is the method that produces the highest monodispersion in geometry and material quality, with the added benefits of being low-temperature, low-cost, easily scalable and of allowing control of the surface coverage of the deposited particles. In this paper, novel plasmonic back-reflector structures were developed using spherical gold colloids with appropriate dimensions for pronounced far-field scattering. The plasmonic back reflectors are incorporated in the rear contact of thin film n-i-p nanocrystalline silicon solar cells to boost their photocurrent generation via optical path length enhancement inside the silicon layer. The quantum efficiency spectra of the devices revealed a remarkable broadband enhancement, resulting from both light scattering from the metal nanoparticles and improved light incoupling caused by the hemispherical corrugations at the cells' front surface formed from the deposition of material over the spherically shaped colloids.

Nunes, D., T. R. Calmeiro, S. Nandy, JV Pinto, A. Pimentel, P. Barquinha, P. A. Carvalho, J. C. Walmsley, E. Fortunato, and R. Martins. "{Charging effects and surface potential variations of Cu-based nanowires}." Thin Solid Films (2015): 1-9. AbstractWebsite

The presentwork reports charging effects and surface potential variations in pure copper, cuprous oxide and cu- pric oxide nanowires observed by electrostatic force microscopy (EFM) and Kelvin probe force microscopy (KPFM). The copper nanowires were produced by wet synthesis, oxidation into cuprous oxide nanowires was achieved throughmicrowave irradiation and cupric oxide nanowireswere obtained via furnace annealing in at- mospheric conditions. Structural characterization of the nanowireswas carried out byX-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy. During the EFM experiments the electrostatic field of the positive probe charged negatively the Cu-based nanowires, which in turn polarized the SiO2 dielectric substrate. Both the probe/nanowire capacitance as well as the sub- strate polarization increased with the applied bias. Cu2O and CuO nanowires behaved distinctively during the EFMmeasurements in accordancewith their band gap energies. Thework functions(WF) of the Cu-based nano- wires, obtained by KPFM measurements, yieldedWFCuO N WFCu N WFCu2O

Aroso, Ivo M., Ana Rita C. Duarte, Ricardo R. Pires, João F. Mano, and Rui L. Reis. "{Cork processing with supercritical carbon dioxide: Impregnation and sorption studies}." Journal of Supercritical Fluids. 104 (2015): 251-258. AbstractWebsite

Abstract The present study relates to the use of supercritical carbon dioxide (SCCO{\textless}inf{\textgreater}2{\textless}/inf{\textgreater}) to modify the properties of cork by incorporation of new molecules. The impact of SCCO{\textless}inf{\textgreater}2{\textless}/inf{\textgreater}processing on the morphology and on the mechanical properties was found to be negligible.The impregnation of disperse blue 14 (blue dye) on cubic shaped cork samples of 5 mm occurs progressively,is dependent of the processing conditions and of the presence of lenticels and growth rings. The impregnation of the samples bulk was achieved with processing at 10 MPa and 313 K for 16 h. The solubility and sorption of SCCO{\textless}inf{\textgreater}2{\textless}/inf{\textgreater} in the cork matrix was measured using circular discs and the diffusion coefficients calculated to be on the order of 10{\textless}sup{\textgreater}-8{\textless}/sup{\textgreater} cm{\textless}sup{\textgreater}2{\textless}/sup{\textgreater}/s, the same order as for wood materials. This work demonstrates the feasibility of supercritical fluid technology to impart new features to cork, which may lead to innovative architectural, outdoor and industrial applications.

Kololuoma, Terho, Jaakko Leppäniemi, Himadri Majumdar, Rita Branquinho, Elena Herbei-Valcu, Viorica Musat, Rodrigo Martins, Elvira Fortunato, and Ari Alastalo. "{Gravure printed sol–gel derived AlOOH hybrid nanocomposite thin films for printed electronics}." J. Mater. Chem. C. 3 (2015): 1776-1786. AbstractWebsite

We report a sol-gel approach to fabricate aluminum-oxy-hydroxide (AlOOH) -based inks for gravure printing of high-dielectric-constant nanocomposite films. By reacting 3-glycidoxypropyl- trimethoxysilane (GPTS) with aluminum-oxide-hydroxide (AlOOH) nanoparticles under constant bead milling, inks suitable for gravure printing were obtained. The calculated relative dielectric constant based on measured capacitances and film thicknesses for the gravure-printed GPTS:AlOOH nanocomposite varied between 7 and 11 at a 10 kHz frequency. The dielectric constant depended on the mixing ratio of the composite and was found to follow the Maxwell-Garnett ternary-system mixing rule indicating presence of micro/nanopores that affect the electrical properties of the fabricated films. Increasing leakage current with increasing AlOOH content was observed. High leakage current was reduced by printing two-layer films. The double-layered gravure-coated films exhibited similar capacitance density but clearly lower leakage current and less electrical breakdowns in comparison to single-layered films having comparable film compositions and film thicknesses. The best composite yielded a capacitance density of 109 ± 2 pF/mm2 at the 10 kHz frequency and a leakage current density of 60 ± 20 µA/cm2 at 0.5 MV/cm electric field as a single layer. The calculated relative dielectric constant at the 10 kHz frequency for this composition was 11.2 ± 0.5. Introduction

Tobias, I., MJ Mendes, A. Boronat, E. Lopez, P. Garcia-Linares, I. Artacho, A. Marti, S. Silvestre, and A. Luque. "{HIT intermediate-band solar cells with self-assembled colloidal quantum dots and metal nanoparticles}." 2015 IEEE 42nd Photovoltaic Specialist Conference, PVSC 2015. 2015. Abstract
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Guerra, M., P. Amaro, J. Machado, and J. P. Santos. "{Modified Binary-Encounter-Bethe Model for Electron Impact Ionization Cross Sections of Highly Charged Ions}." Vol. 635. Journal of Physics: Conference Series, 2015. 052067. Abstract
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Alexa, A., N. Tigau, P. Alexandru, A. Pimentel, R. Branquinho, D. Salgueiro, T. Calmeiro, R. Martins, E. Fortunato, and V. Musat. "{Morphological and optical characterization of transparent thin films obtained at low temperature using ZnO nanoparticles}." Journal of Optoelectronic and Advanced Materials. 17 (2015): 1288-1295. Abstract

Transparent metal oxides thin films are a class of inorganic conductors and semiconductors with significant importance for use in portable electronics, displays, flexible electronics, multi-functional windows and solar cells. Due to the recent development of transparent and flexible electronics, there is a growing interest in depositing metal-oxide thin-film on plastic substrates that can offer flexibility, lighter weight, and potentially lead to cheaper manufacturing by allowing printing and roll- to-roll processing. The plastic substrates, however, limit device processing to below 200oC. In this context, the deposition of high-performance semiconductor thin films from dispersions of pre-prepared oxide nanoparticles at temperatures below 200oC represents a potential key route. This paper reports on the preparation of ZnO transparent thin films using solution- processed nanoparticles (NPs) precipitated from zinc acetate alcoholic solution with potassium hydroxide. The nanoparticles size distribution, microstructure and crystallinity were measured by dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The thin films were deposited by spin-coating onto soda lima glass substrate, using a dispersion of 1wt{%} ZnO NPs. The morphology of the films annealed at 120 and 180oC, observed by atomic force microscopy and cross-section scanning electron microscopy, shows columnar grains with diameter ranging between 20 and 70 nm, depending on the conditions of depositions. Optical measurements indicated high transparency, between 85 and 94 {%}, in the visible range, a direct nature of band-to-band transitions and band gap values between 3,22 and 3,32 eV. The refractive index and extinction coefficient have been calculated from optical transmittance and reflectance spectra.

Lyubchyk, A., SA Filonovich, T. Mateus, MJ Mendes, A. Vicente, JP Leitão, BP Falcão, E. Fortunato, H. Águas, and R. Martins. "{Nanocrystalline thin film silicon solar cells: A deeper look into p/i interface formation}." Thin Solid Films (2015). AbstractWebsite
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Quraishi, Sakeena, Marta Martins, Alexandre A. Barros, Pavel Gurikov, S. P. Raman, Irina Smirnova, Ana Rita C. Duarte, and Rui L. Reis. "{Novel non-cytotoxic alginate–lignin hybrid aerogels as scaffolds for tissue engineering}." Journal of Supercritical Fluids. 105 (2015): 1-8. AbstractWebsite

This paper presents a novel approach toward the production of hybrid alginate–lignin aerogels. The key idea of the approach is to employ pressurized carbon dioxide for gelation. Exposure of alginate and lignin aqueous alkali solution containing calcium carbonate to CO2at 4.5 MPa resulted in a hydrogel formation. Various lignin and CaCO3concentrations were studied. Stable hydrogels could be formed up to 2:1 (w/w) alginate-to-lignin ratio (1.5 wt{%} overall biopolymer concentration). Upon substitution of water with ethanol, gels were dried in supercritical CO2to produce aerogels. Aerogels with bulk density in the range 0.03–0.07 g/cm3, surface area up to 564 m2/g and pore volume up to 7.2 cm3/g were obtained. To introduce macroporosity, the CO2induced gelation was supplemented with rapid depressurization (foaming process). Macroporosity up to 31.3 ± 1.9{%} with interconnectivity up to 33.2 ± 8.3{%} could be achieved at depressurization rate of 3 MPa/min as assessed by micro-CT. Young's modulus of alginate–lignin aerogels was measured in both dry and wet states. Cell studies revealed that alginate–lignin aerogels are non-cytotoxic and feature good cell adhesion making them attractive candidates for a wide range of applications including tissue engineering and regenerative medicine.

Kiazadeh, Asal, Daniela Salgueiro, Rita Branquinho, Joana Pinto, Henrique L. Gomes, Pedro Barquinha, Rodrigo Martins, and Elvira Fortunato. "{Operational stability of solution based zinc tin oxide/SiO2 thin film transistors under gate bias stress}." APL Materials. 3 (2015): 062804. AbstractWebsite

In this study, we report solution-processed amorphous zinc tin oxide transistors exhibiting high operational stability under positive gate bias stress, translated by a recoverable threshold voltage shift of about 20{%} of total applied stress voltage. Under vacuum condition, the threshold voltage shift saturates showing that the gate-bias stress is limited by trap exhaustion or balance between trap filling and emptying mechanism. In ambient atmosphere, the threshold voltage shift no longer saturates, stability is degraded and the recovering process is impeded. We suggest that the trapping time during the stress and detrapping time in recovering are affected by oxygen adsorption/desorption processes. The time constants extracted from stretched exponential fitting curves are ≈106 s and 105 s in vacuum and air, respectively.

Nunes, D., A. Pimentel, JV Pinto, T. R. Calmeiro, S. Nandy, P. Barquinha, L. Pereira, P. A. Carvalho, E. Fortunato, and R. Martins. "{Photocatalytic behavior of TiO2 films synthesized by microwave irradiation}." Catalysis Today (2015). AbstractWebsite
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Schuster, Christian S., Seweryn Morawiec, Manuel J. Mendes, Maddalena Patrini, Emiliano R. Martins, Liam Lewis, Isodiana Crupi, and Thomas F. Krauss. "{Plasmonic and diffractive nanostructures for light trapping - an experimental comparison}." Optica. 2 (2015): 194-200. AbstractWebsite

Metal nanoparticles and diffractive nanostructures are widely studied for enhancing light trapping efficiency in thin-film solar cells. Both have achieved high performance enhancements, but there are very few direct comparisons between the two. Also, it is difficult to accurately determine the parasitic absorption of metal nanoparticles. Here, we assess the light trapping efficiencies of both approaches in an identical absorber configuration. We use a 240 nm thick amorphous silicon slab as the absorber layer and either a quasi-random supercell diffractive nanostructure or a layer of self-assembled metal nanoparticles for light trapping. Both the plasmonic and diffractive structures strongly enhance the absorption in the red/near-infrared regime. At longer wavelengths, however, parasitic absorption becomes evident in the metal nanoparticles, which reduces the overall performance of the plasmonic approach. We have formulated a simple analytical model to assess the parasitic absorption and effective reflectivity of a plasmonic reflector and to demonstrate good agreement with the experimental data.