Export 878 results:
Sort by: Author Title Type [ Year  (Desc)]
2017
Lourenço, P., B. J. Guerreiro, P. Batista, P. Oliveira, and C. Silvestre. "Sensing and Control for Autonomous Vehicles: Applications to Land, Water and Air Vehicles." Eds. Thor I. Fossen, Kristin Y. Pettersen, and Henk Nijmeijer. Springer, 2017. 121-141. Abstract
n/a
Lourenço, P., B. J. Guerreiro, P. Batista, P. Oliveira, and C. Silvestre. "Sensing and Control for Autonomous Vehicles: Applications to Land, Water and Air Vehicles." Eds. Thor I. Fossen, Kristin Y. Pettersen, and Henk Nijmeijer. Springer, 2017. 121-141. Abstract
n/a
Ripple, W. J., C. Wolf, T. M. Newsome, M. Galetti, M. Alamgir, E. Crist, M. I. Mahmoud, W. F. Laurance, and +15364 signatoriesscientist. "World Scientists’ Warning to Humanity: A Second Notice." BioScience. 125 (2017). Abstract
n/a
Pimentel, A., A. Araújo, B. J. Coelho, D. Nunes, M. J. Oliveira, MJ Mendes, H. Águas, R. Martins, and E. Fortunato. "{3D ZnO/Ag surface-enhanced Raman scattering on disposable and flexible cardboard platforms}." Materials. 10 (2017). Abstract

© 2017 by the authors. In the present study, zinc oxide (ZnO) nanorods (NRs) with a hexagonal structure have been synthesized via a hydrothermal method assisted by microwave radiation, using specialized cardboard materials as substrates. Cardboard-type substrates are cost-efficient and robust paper-based platforms that can be integrated into several opto-electronic applications for medical diagnostics, analysis and/or quality control devices. This class of substrates also enables highly-sensitive Raman molecular detection, amiable to several different operational environments and target surfaces. The structural characterization of the ZnO NR arrays has been carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM) and optical measurements. The effects of the synthesis time (5-30 min) and temperature (70-130 °C) of the ZnO NR arrays decorated with silver nanoparticles (AgNPs) have been investigated in view of their application for surface-enhanced Raman scattering (SERS) molecular detection. The size and density of the ZnO NRs, as well as those of the AgNPs, are shown to play a central role in the final SERS response. A Raman enhancement factor of 7 × 105was obtained using rhodamine 6 G (RG6) as the test analyte; a ZnO NR array was produced for only 5 min at 70 °C. This condition presents higher ZnO NR and AgNP densities, thereby increasing the total number of plasmonic "hot-spots", their volume coverage and the number of analyte molecules that are subject to enhanced sensing.

Pohl, Randolf, Fran{\c c}ois Nez, Luis M. P. Fernandes, Marwan Abdou Ahmed, Fernando D. Amaro, Pedro Amaro, Fran{\c c}ois Biraben, João M. R. Cardoso, Daniel S. Covita, Andreas Dax, Satish Dhawan, Marc Diepold, Beatrice Franke, Sandrine Galtier, Adolf Giesen, Andrea L. Gouvea, Johannes Götzfried, Thomas Graf, Theodor W. Hänsch, Malte Hildebrandt, Paul Indelicato, Lucile Julien, Klaus Kirch, Andreas Knecht, Paul Knowles, Franz Kottmann, Julian J. Krauth, Eric-Olivier Le Bigot, Yi-Wei Liu, José A. M. Lopes, Livia Ludhova, Jorge Machado, Cristina M. B. Monteiro, Fran{\c c}oise Mulhauser, Tobias Nebel, Paul Rabinowitz, Joaquim M. F. dos Santos, José Paulo Santos, Lukas A. Schaller, Karsten Schuhmann, Catherine Schwob, Csilla I. Szabo, David Taqqu, João F. C. A. Veloso, Andreas Voss, Birgit Weichelt, and Aldo Antognini. "{Laser Spectroscopy of Muonic Atoms and Ions}." Proceedings of the 12th International Conference on Low Energy Antiproton Physics (LEAP2016). Journal of the Physical Society of Japan, 2017. Abstract
n/a
Pardal, T., S. Messias, M. Sousa, A. S. R. Machado, C. M. Rangel, D. Nunes, JV Pinto, R. Martins, and M. N. {Da Ponte}. "{Syngas production by electrochemical CO2 reduction in an ionic liquid based-electrolyte}." Journal of CO2 Utilization. 18 (2017). Abstract

© 2017 Elsevier Ltd. Graphical abstract: The electrochemical reduction of carbon dioxide dissolved in a solution of water and ionic liquid as electrolyte, at high-pressure and near room-temperature, is reported. This work describes an electro-deposition strategy for the preparation of copper substrate cathodes, coated with bimetallic zinc-copper films, obtained from deep-eutectic solvents plating baths. The prepared bimetallic cathodes showed electrochemical activity for syngas production in 1-butyl-3-methylimidazolium triflate, with yields of 85N$μ$L (normal microliter)cm−2C−1/170N$μ$Lcm−2h−1, high selectivities, tunable H2/CO ratio and low energetic requirements.

Goswami, S., S. Nandy, A. N. Banerjee, A. Kiazadeh, G. R. Dillip, JV Pinto, S. W. Joo, R. Martins, and E. Fortunato. "{“Electro-Typing” on a Carbon-Nanoparticles-Filled Polymeric Film using Conducting Atomic Force Microscopy}." Advanced Materials. 29 (2017). Abstract

© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Next-generation electrical nanoimprinting of a polymeric data sheet based on charge trapping phenomena is reported here. Carbon nanoparticles (CNPs) (waste carbon product) are deployed into a polymeric matrix (polyaniline) (PANI) as a charge trapping layer. The data are recorded on the CNPs-filled polyaniline device layer by “electro-typing” under a voltage pulse (VET, from ±1 to ±7 V), which is applied to the device layer through a localized charge-injection method. The core idea of this device is to make an electrical image through the charge trapping mechanism, which can be “read” further by the subsequent electrical mapping. The density of stored charges at the carbon–polyaniline layer, near the metal/polymer interface, is found to depend on the voltage amplitude, i.e., the number of injected charge carriers. The relaxation of the stored charges is studied by different probe voltages and for different devices, depending on the percolation of the CNPs into the PANI. The polymeric data sheet retains the recorded data for more than 6 h, which can be refreshed or erased at will. Also, a write–read–erase–read cycle is performed for the smallest “bit” of stored information through a single contact between the probe and the device layer.

2016
Lorenz, M., et al. "{The 2016 oxide electronic materials and oxide interfaces roadmap}." Journal of Physics D: Applied Physics. 49 (2016): 433001. AbstractWebsite

Oxide electronic materials provide a plethora of possible applications and offer ample opportunity for scientists to probe into some of the exciting and intriguing phenomena exhibited by oxide systems and oxide interfaces. In addition to the already diverse spectrum of properties, the nanoscale form of oxides provides a new dimension of hitherto unknown phenomena due to the increased surface-to-volume ratio. Oxide electronic materials are becoming increasingly important in a wide range of applications including transparent electronics, optoelectronics, magnetoelectronics, photonics, spintronics, thermoelectrics, piezoelectrics, power harvesting, hydrogen storage and environmental waste management. Synthesis and fabrication of these materials, as well as processing into particular device structures to suit a specific application is still a challenge. Further, characterization of these materials to understand the tunability of their properties and the novel properties that evolve due to their nanostructured nature is another facet of the challenge. The research related to the oxide electronic field is at an impressionable stage, and this has motivated us to contribute with a roadmap on 'oxide electronic materials and oxide interfaces'. This roadmap envisages the potential applications of oxide materials in cutting edge technologies and focuses on the necessary advances required to implement these materials, including both conventional and novel techniques for the synthesis, characterization, processing and fabrication of nanostructured oxides and oxide-based devices. The contents of this roadmap will highlight the functional and correlated properties of oxides in bulk, nano, thin film, multilayer and heterostructure forms, as well as the theoretical considerations behind both present and future applications in many technologically important areas as pointed out by Venkatesan. The contributions in this roadmap span several thematic groups which are represented by the following authors: novel field effect transistors and bipolar devices by Fortunato, Grundmann, Boschker, Rao, and Rogers; energy conversion and saving by Zaban, Weidenkaff, and Murakami; new opportunities of photonics by Fompeyrine, and Zuniga-Perez; multiferroic materials including novel phenomena by Ramesh, Spaldin, Mertig, Lorenz, Srinivasan, and Prellier; and concepts for topological oxide electronics by Kawasaki, Pentcheva, and Gegenwart. Finally, Miletto Granozio presents the European action 'towards oxide-based electronics' which develops an oxide electronics roadmap with emphasis on future nonvolatile memories and the required technologies. In summary, we do hope that this oxide roadmap appears as an interesting up-to-date snapshot on one of the most exciting and active areas of solid state physics, materials science, and chemistry, which even after many years of very successful development shows in short intervals novel insights and achievements.

Röder, Marko, et al. "{Coulomb dissociation of $^{20,21}$N}." Physical Review C. 93 (2016): 065807. AbstractWebsite
n/a
Panigrahi, Shrabani, Tomas Calmeiro, Rodrigo Martins, Daniela Nunes, and Elvira Fortunato. "{Observation of Space Charge Dynamics Inside an All Oxide Based Solar Cell}." ACS NANO. 10 (2016): 6139-6146. Abstract
n/a
Barrocas, B., S. Sério, A. Rovisco, Y. Nunes, and Melo M. E. Jorge. "{Removal of rhodamine 6G dye contaminant by visible light driven immobilized Ca1⿿Ln MnO3 (Ln = Sm, Ho; 0.1 ⿤x⿤ 0.4) photocatalysts}." Applied Surface Science. 360 (2016): 798-806. AbstractWebsite

Visible-light-driven Ca1-xLnxMnO3 (Ln=Sm, Ho; 0.1≤x≤0.4) films were grown by RF- magnetron sputtering onto fused silica substrates. The effects of Ca2+ substitution for Ho3+ or Sm3+ in Ca1-xLnxMnO3 on the structural, morphological and photocatalytic properties for Rhodamine 6G dye degradation under visible light irradiation were investigated. XRD showed a pure typical perovskite phase for all the prepared films, except for Ca0.9Ho0.1MnO3 and a decrease of the crystallite size with the increase of the amount of ion substituted. SEM and AFM revealed that the films surface is dense, with low roughness. UV-vis spectroscopy indicated for the two series band gaps in the range of 1.6 - 2.8eV, being lower for the films containing holmium. The results showed that some Ca1-xHoxMnO3 and Ca1-xSmxMnO3 films present higher photocatalytic activity for Rh6G degradation in comparison with TiO2 films and for the same x value the Ho-films exhibited higher photocatalytic activity. For both films series the maximal degradation rate was obtained for x=0.2; above this content the degradation percentage exhibits a decreasing trend with the increase of Ho or Sm substitution, except for x=0.4 in the case of Ho system, which is observed again an increase in the degradation rate. The Rh6G photocatalytic degradation followed a pseudo first-order reaction kinetics. XRD and SEM of the used photocatalysts evidenced high photochemical stability.

Nobrega, C. S., I. H. Saraiva, C. Carreira, B. Devreese, M. Matzapetakis, and S. R. Pauleta. "The solution structure of the soluble form of the lipid-modified azurin from Neisseria gonorrhoeae, the electron donor of cytochrome c peroxidase." Biochim Biophys Acta. 1857 (2016): 169-76. AbstractWebsite

Neisseria gonorrhoeae colonizes the genitourinary track, and in these environments, especially in the female host, the bacteria are subjected to low levels of oxygen, and reactive oxygen and nitrosyl species. Here, the biochemical characterization of N. gonorrhoeae Laz is presented, as well as, the solution structure of its soluble domain determined by NMR. N. gonorrhoeae Laz is a type 1 copper protein of the azurin-family based on its spectroscopic properties and structure, with a redox potential of 277+/-5 mV, at pH7.0, that behaves as a monomer in solution. The globular Laz soluble domain adopts the Greek-key motif, with the copper center located at one end of the beta-barrel coordinated by Gly48, His49, Cys113, His118 and Met122, in a distorted trigonal geometry. The edge of the His118 imidazole ring is water exposed, in a surface that is proposed to be involved in the interaction with its redox partners. The heterologously expressed Laz was shown to be a competent electron donor to N. gonorrhoeae cytochrome c peroxidase. This is an evidence for its involvement in the mechanism of protection against hydrogen peroxide generated by neighboring lactobacilli in the host environment.

Brás, Joana L. A., Benedita A. Pinheiro, Kate Cameron, Fiona Cuskin, Aldino Viegas, Shabir Najmudin, Pedro Bule, Virginia M. R. Pires, Maria João Romão, Edward A. Bayer, Holly L. Spencer, Steven Smith, Harry J. Gilbert, Victor D. Alves, Ana Luísa Carvalho, and Carlos M. G. A. Fontes. "Diverse specificity of cellulosome attachment to the bacterial cell surface." Scientific Reports. 6 (2016): 38292. AbstractWebsite

During the course of evolution, the cellulosome, one of Nature's most intricate multi-enzyme complexes, has been continuously fine-tuned to efficiently deconstruct recalcitrant carbohydrates. To facilitate the uptake of released sugars, anaerobic bacteria use highly ordered protein-protein interactions to recruit these nanomachines to the cell surface. Dockerin modules located within a non-catalytic macromolecular scaffold, whose primary role is to assemble cellulosomal enzymatic subunits, bind cohesin modules of cell envelope proteins, thereby anchoring the cellulosome onto the bacterial cell. Here we have elucidated the unique molecular mechanisms used by anaerobic bacteria for cellulosome cellular attachment. The structure and biochemical analysis of five cohesin-dockerin complexes revealed that cell surface dockerins contain two cohesin-binding interfaces, which can present different or identical specificities. In contrast to the current static model, we propose that dockerins utilize multivalent modes of cohesin recognition to recruit cellulosomes to the cell surface, a mechanism that maximises substrate access while facilitating complex assembly.

Neca, A. J., R. Soares, M. S. Carepo, and S. R. Pauleta. "Resonance assignment of DVU2108 that is part of the Orange Protein complex in Desulfovibrio vulgaris Hildenborough." Biomol NMR Assign. 10 (2016): 117-20. AbstractWebsite

We report the 94 % assignment of DVU2108, a protein belonging to the Orange Protein family, that in Desulfovibrio vulgaris Hildenborough forms a protein complex named the Orange Protein complex. This complex has been shown to be implicated in the cell division of this organism. DVU2108 is a conserved protein in anaerobic microorganisms and in Desulfovibrio gigas the homologous protein was isolated with a novel Mo-Cu cluster non-covalently attached to the polypeptide chain. However, the heterologously produced DVU2108 did not contain any bound metal. These assignments provide the means to characterize the interaction of DVU2108 with the proteins that form the Orange Protein complex using NMR methods.

Kardarian, Kasra, Daniela Nunes, Paolo {Maria Sberna}, Adam Ginsburg, David A. Keller, Joana {Vaz Pinto}, Jonas Deuermeier, Assaf Y. Anderson, Arie Zaban, Rodrigo Martins, and Elvira Fortunato. "{Effect of Mg doping on Cu2O thin films and their behavior on the TiO2/Cu2O heterojunction solar cells}." Solar Energy Materials and Solar Cells. 147 (2016): 27-36. AbstractWebsite

Abstract The present work shows the effect of magnesium doping on structural, optoelectrical and electrical properties of Cu2O thin films prepared by spray pyrolysis. The variation in the concentration of Mg shows significant impact on the final thin film properties, whereas the film doped with 0.5 at{%} of Mg exhibited major property improvements in comparison with the undoped thin film and among the other concentrations tested. This condition was further applied for the deposition of an absorber layer in a heterojunction solar cell array with a gradient in thicknesses of active layers to investigate the impact of changing thicknesses on the PV parameters of the solar cell. TiO2 was used as a window layer and the 0.5 at{%} Cu2O doped film as an absorber layer. The produced heterojunction solar cell array was further exposed to a rapid thermal annealing treatment. The I–V measurements show an open circuit voltage of up to 365 mV and a short circuit current density, which is dependent on absorber layer thickness, and reaches to a maximum value of 0.9 mA/cm2.

Biscaia, Hugo, Carlos Chastre, David Cruz, Noel Franco, and Ricardo Nunes. "Avaliação experimental de diferentes ligações coladas." TEST&E 2016 - 1º Congresso de Ensaios e Experimentação em Engenharia Civil. IST, Lisbon, Portugal 2016. 8. Abstractteste2016_-_01050_-_biscaia.pdf

A utilização de materiais compósitos de matriz polimérica (Fiber Reinforced Polymers - FRP) como armadura de reforço de diferentes elementos estruturas de várias naturezas (e.g. betão armado, aço, madeira ou alvenaria) tem vindo a suscitar o interesse da comunidade científica internacional. Inicialmente, a simples colagem pelo exterior dos compósitos de FRP aos elementos estruturais permitiu identificar um fenómeno de descolamento prematuro do compósito para níveis de extensão muito aquém dos seus limites de rotura. Com base na experimentação, algumas teorias têm surgido no sentido de explicar o fenómeno do descolamento prematuro dos FRPs. Por outro lado, outras técnicas de reforço têm sido propostas com o objetivo de adiar ou simplesmente eliminar esse fenómeno. Neste trabalho, são analisadas diferentes ligações coladas entre laminados de CFRP e outros materiais tais como, o betão armado, o aço e a madeira. Duas técnicas de reforço por colagem vulgarmente citadas na literatura internacional foram utilizadas: Externally Bonded Reinforcement (EBR) e Near Surface Mounted (NSM). Os resultados experimentais permitiram constatar que o desempenho local das ligações estudadas é distinto, tendo-se observado que as relações entre a tensão de aderência e o deslocamento relativo entre superfícies é: (i) na ligação CFRP/betão do tipo não linear e caracteriza-se por, após atingir-se uma tensão de aderência máxima, o descolamento ocorre quando a tensão de aderência tende para zero; (ii) na ligação CFRP/aço o desempenho é do tipo bi-linear, i.e. com um troço inicial retilíneo até atingir-se uma tensão de pico seguindo-se um troço linear descendente até tensão de aderência nula; e (iii) na ligação CFRP/madeira o desempenho é do tipo tri-linear, i.e. similar à ligação CFRP/aço mas com um troço constante a seguir ao troço linear descendente e que se esgota para um deslocamento relativo último.

Biscaia, Hugo, Carlos Chastre, David Cruz, Noel Franco, and Ricardo Nunes. "Reforço à flexão de pavimentos antigos de madeira com recurso a laminados de fibras de carbono." TEST&E 2016 - 1º Congresso de Ensaios e Experimentação em Engenharia Civil. IST, Lisbon, Portugal 2016. 8. Abstractteste2016_-_01049_-_biscaia.pdf

O dimensionamento de vigas de madeira aos Estados Limites de Utilização (ELUt) tem limites muito apertados tanto para ações de curto prazo como para ações de longo prazo. Uma solução eficiente para este problema passa por aumentar as seções transversais das vigas. Porém, este tipo de solução não só acarreta um aumento de custos como também altera profundamente arquitetura original do edifício abrindo, por conseguinte, uma oportunidade para encontrar outras soluções mais eficientes. Neste sentido, o uso de armaduras de reforço em vigas de madeira pode ser considerado como uma solução promissora uma vez que as estruturas, novas ou velhas, manteriam o aspeto estético original sem introduzir nos elementos reforçados, um aumento significativo do seu peso próprio, melhorando o seu desempenho face a ações de curto e longo prazo. O presente estudo é dedicado à análise de vigas de madeira antigas reforçadas à flexão com materiais compósitos de fibras de carbono, vulgarmente designados na literatura internacional por Carbon Fiber Reinforced Polymers (CFRP). Neste trabalho, foram reforçados e ensaiados à flexão pavimentos antigos de madeira tendo-se analisado os respetivos desempenhos aquando da utilização de uma técnica de reforço por colagem tradicional (Externally Bonded Reinforcement - EBR) e aquando da utilização de uma técnica de reforço por colagem inovadora (Continous Reinforcement Embedded at Ends - CREatE). Os ensaios experimentais permitiram verificar que a técnica de colagem inovadora CREatE confere aos pavimentos de madeira uma maior rigidez e resistência face à técnica tradicional conseguindo se mobilizar a totalidade do compósito de CFRP.

Nunes, Henrique, Paula Couto, Maria João Silva, and Fernando Pinho. "Proposta de Sistema de Classificação Nacional orientado para objetos BIM." 1º Congresso Português de Building Information Modelling. ISBN: 978-989-8793-04-1. DOI 10.5281/zenodo.166758. Universidade do Minho, Guimarães 2016.
Noack, F., P. Katranuschkov, R. Scherer, V. Dimitriou, SK Firth, TM Hassan, N. Ramos, P. Pereira, P. Maló, and T. Fernando Technical challenges and approaches to transfer building information models to building energy. Eds. Symeon E. Christodoulou, and Raimar Scherer. Proceedings of ECPPM 2016. CRC Press, 2016. Abstract

The complex data exchange between architectural design and building energy simulation constitutes the main challenge in the use of energy performance analyses in the early design stage. The enhancement of BIM model data with additional specific energy-related information and the subsequent mapping to the input of an energy analysis or simulation tool is yet an open issue. This paper examines three approaches for the data transfer from 3D CAD applications to building performance simulations using BIM as central data repository and points out their current and envisaged use in practice. The first approach addresses design scenarios. It focuses on the supporting tools needed to achieve interoperability given a 74 wide-spread commercial BIM model (Autodesk Revit) and a dedicated pre-processing tool (DesignBuilder) for EnergyPlus. The second approach is similar but addresses retrofitting scenarios. In both workflows gbXML is used as the transformation format. In the third approach a standard BIM model, IFC is used as basis for the transfer process for any relevant lifecycle phase.

Faustino, Pedro, Carlos Chastre, Ângela Nunes, and Ana Brás. "Lifetime modelling of chloride induced corrosion in reinforced concrete structures with concrete with portland and blended cements." Structure and Infrastructure Engineering. 12 (2016): 1013-1023. AbstractWebsite

This article discusses mathematical modelling of the long-term performance of concrete with different supplementary cementitious materials in a maritime environment. The research was carried out in the light of the national Portuguese application of the CEN standards with mandatory requirements for a performance-based design approach. Laboratory investigations were performed on concrete compositions based on CEM I and CEM II/B-L in which the cement was partially replaced by either 0% (reference composition) or 50% of low calcium fly ash (FA). Concrete compositions were made with the objective to achieve service lives of 50 and 100 years with regard to steel corrosion. Test results of compressive strength, chloride potential diffusion and electrical resistivity are reported for different curing ages of 28, 90, 180 and 365 days. Chloride diffusion results were used for the implementation of modelling equations in order to estimate the design lifetime regarding reinforcing steel corrosion. A performance-based approach using a probabilistic method was carried out and the results obtained are compared with the requirements according to the Portuguese prescriptive approach. The modelling results show that FA blended compositions have better performance compared to those with Portland cements, especially if curing ages beyond 28 days are considered.

Nowacki, Blazej, Nuno Paulino, and João Goes A 1V 77dB-DR 72dB-SNDR 10MHz-BW 2-1 MASH CT ΣΔM. IEEE International Solid-State Circuits Conference (ISSCC’16). San Francisco, USA: IEEE, 2016.
Correia, Isabel, Stefan Nickel, and Francisco Saldanha-da-Gama. "A Modeling Framework for Stochastic Multi-Period Capacitated Multiple Allocation Hub Location." ILS 2016 Conference - Information Systems, Logistics and Supply Chain. 2016. Abstract

n/a

Batista, AG, S. Najdi, D. M. Godinho, F. Serrano, M. D. Ortigueira, and R. T. Rato. "A Multichannel Time-Frequency and Multi-Wavelet Toolbox for Uterine Electromyography Processing and Visualisation." Computers in Biology and Medicine. 76.1 (2016): 178-191.