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2014
Pereira, L., D. Gaspar, D. Guerin, a Delattre, E. Fortunato, and R. Martins. "{The influence of fibril composition and dimension on the performance of paper gated oxide transistors.}." Nanotechnology. 25 (2014): 094007. AbstractWebsite

Paper electronics is a topic of great interest due the possibility of having low-cost, disposable and recyclable electronic devices. The final goal is to make paper itself an active part of such devices. In this work we present new approaches in the selection of tailored paper, aiming to use it simultaneously as substrate and dielectric in oxide based paper field effect transistors (FETs). From the work performed, it was observed that the gate leakage current in paper FETs can be reduced using a dense microfiber/nanofiber cellulose paper as the dielectric. Also, the stability of these devices against changes in relative humidity is improved. On other hand, if the pH of the microfiber/nanofiber cellulose pulp is modified by the addition of HCl, the saturation mobility of the devices increases up to 16 cm(2) V(-1) s(-1), with an ION/IOFF ratio close to 10(5).

Guerreiro, B. J., C. Silvestre, R. Cunha, and A. Pascoal. "{Trajectory Tracking Nonlinear Model Predictive Control for Autonomous Surface Craft}." Transactions in Control Systems Technology. 22 (2014): 2160-2175. Abstract
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Guerreiro, B. J., C. Silvestre, R. Cunha, and A. Pascoal. "{Trajectory Tracking Nonlinear Model Predictive Control for Autonomous Surface Craft}." Transactions in Control Systems Technology. 22 (2014): 2160-2175. Abstract
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2013
Chemetov, N. V., and F. Cipriano. "The Inviscid Limit for the Navier-Stokes Equations with Slip Condition on Permeable Walls." JOURNAL OF NONLINEAR SCIENCE. 23 (2013): 731-750. Abstract

{We consider the Navier-Stokes equations in a 2D-bounded domain with general non-homogeneous Navier slip boundary conditions prescribed on permeable boundaries, and study the vanishing viscosity limit. We prove that solutions of the Navier-Stokes equations converge to solutions of the Euler equations satisfying the same Navier slip boundary condition on the inflow region of the boundary. The convergence is strong in Sobolev's spaces , which correspond to the spaces of the data.}

Li, Lidong, Patricia S. Lopes, Claudia A. Figueira, Clara S. B. Gomes, M. Teresa Duarte, Vitor Rosa, Christophe Fliedel, Teresa Aviles, and Pedro T. Gomes. "{Cationic and Neutral (Ar-BIAN) Copper( I) Complexes Containing Phosphane and Arsane Ancillary Ligands: Synthesis, Molecular Structure and Catalytic Behaviour in Cycloaddition Reactions of Azides and Alkynes}." {EUROPEAN JOURNAL OF INORGANIC CHEMISTRY} (2013): {1404-1417}. Abstract

{{A series of new cationic and neutral (Ar-BIAN) copper(I) complexes {[}in which Ar-BIAN = bis(aryl)acenaphthenequinonediimine] was synthesised and characterised by elemental analysis, 1D and 2D NMR spectroscopy and single-crystal Xray diffraction. The cationic complexes of the general formula {[}Cu(Ar-BIAN)L-2]BF4 {[}L-2 = (PPh3)(2) (1), dppe (2), dppf (3), (AsPh3)(2) (4); Ar = 4-iPrC(6)H(4) (a), 4-MeOC6H4 (b), 4-NO2C6H4 (c), 2-iPrC(6)H(4) (d), Ph2PCH2CH2PPh2 (dppe), (Ph2PC5H4)(2)Fe (dppf)] were synthesised by reaction of {[}Cu(EPh3)(4)]BF4 (E = P or As) and equimolar amounts of Ar-BIAN ligands, or by reaction of equimolar amounts of {[}Cu(NCMe)(4)]BF4, 4-iPrC(6)H(4)-BIAN (a) and diphosphanes dppe or dppf, in dichloromethane, whereas the neutral complexes of the types {[}CuX(Ar-BIAN)(EPh3)] {[}X = Cl

Schnee, Gilles, Christophe Fliedel, Teresa Aviles, and Samuel Dagorne. "{Neutral and Cationic N-Heterocyclic Carbene Zinc Adducts and the BnOH/Zn(C6F5)(2) Binary Mixture - Characterization and Use in the Ring-Opening Polymerization of beta-Butyrolactone, Lactide, and Trimethylene Carbonate}." {EUROPEAN JOURNAL OF INORGANIC CHEMISTRY}. {2013} (2013): {3699-3709}. Abstract

{{Abstract A variety of N-heterocyclic carbene (NHC) zinc adducts of the type NHC-ZnMe2 {[}2a

Chemetov, N. V., and F. Cipriano. "Boundary layer problem: Navier-Stokes equations and Euler equations." NONLINEAR ANALYSIS-REAL WORLD APPLICATIONS. 14 (2013): 2091-2104. Abstract

{This work is concerned with the boundary layer turbulence, which is an outstanding problem in fluid mechanics. We consider an incompressible viscous fluid in 2D domains with permeable walls. The permeability is described by the Yudovich condition. The goal of the article is to study the fluid behavior at vanishing viscosity (large Reynold's numbers). We show that the vanishing viscous limit is a solution of the Euler equations with the Yudovich condition on the inflow region of the boundary. (C) 2013 Elsevier Ltd. All rights reserved.}

Ramos, Tania, Maria Isabel Gomes, and Ana Paula Barbosa-povoa. "Recyclable packaging waste collection systems: redesigning service areas and collection routes in a real case-study." 2nd International Conference WASTES: Solutions, Treatments and Opportunities. Braga, Portugal 2013. Abstract2013_ramosgomesbpovoa_wastes2013.pdf

This paper addresses the planning of a real recyclable packaging waste collection system operating in Portugal. The company’s logistics network is characterized by the existence of multiple depots and multiple products to be collected in each site. Service areas and vehicle routes are currently defined respecting the municipal boundaries and present a need for improvement. To study this problem mixed integer linear programming formulations have been developed allowing the redesign of service areas and of collection routes under two scenarios, respectively, considering the definition of service areas by depot and by material. The scenario where the current service areas are maintained and the collection routes are optimized is also studied. Savings up to 20% in total distance are achieved by redesigning service areas and collection routes.

Nunes de Carvalho, C., P. Parreira, G. Lavareda, P. Brogueira, and A. Amaral. "P-type CuxS thin films: Integration in a thin film transistor structure." THIN SOLID FILMS. 543 (2013): 3-6. Abstract

CuxS thin films, 80 nm thick, are deposited by vacuum thermal evaporation of sulfur-rich powder mixture, Cu2S:S (50:50 wt.%) with no intentional heating of the substrate. The process of deposition occurs at very low deposition rates (0.1-0.3 nm/s) to avoid the formation of Cu or S-rich films. The evolution of CuxS films surface properties (morphology/roughness) under post deposition mild annealing in air at 270 degrees C and their integration in a thin film transistor (TFT) are the main objectives of this study. Accordingly, Scanning Electron Microscopy studies show CuxS films with different surface morphologies, depending on the post deposition annealing conditions. For the shortest annealing time, the CuxS films look to be constructed of grains with large dimension at the surface (approximately 100 nm) and consequently, irregular shape. For the longest annealing time, films with a fine-grained surface are found, with some randomly distributed large particles bound to this fine-grained surface. Atomic Force Microscopy results indicate an increase of the root-mean-square roughness of CuxS surface with annealing time, from 13.6 up to 37.4 nm, for 255 and 345 s, respectively. The preliminary integration of CuxS films in a TFT bottom-gate type structure allowed the study of the feasibility and compatibility of this material with the remaining stages of a TFT fabrication as well as the determination of the p-type characteristic of the CuxS material. (c) 2013 Elsevier B.V. All rights reserved.

Nunes de Carvalho, C., P. Parreira, G. Lavareda, P. Brogueira, and A. Amaral. "P-type CuxS thin films: Integration in a thin film transistor structure." THIN SOLID FILMS. 543 (2013): 3-6. Abstract

CuxS thin films, 80 nm thick, are deposited by vacuum thermal evaporation of sulfur-rich powder mixture, Cu2S:S (50:50 wt.%) with no intentional heating of the substrate. The process of deposition occurs at very low deposition rates (0.1-0.3 nm/s) to avoid the formation of Cu or S-rich films. The evolution of CuxS films surface properties (morphology/roughness) under post deposition mild annealing in air at 270 degrees C and their integration in a thin film transistor (TFT) are the main objectives of this study. Accordingly, Scanning Electron Microscopy studies show CuxS films with different surface morphologies, depending on the post deposition annealing conditions. For the shortest annealing time, the CuxS films look to be constructed of grains with large dimension at the surface (approximately 100 nm) and consequently, irregular shape. For the longest annealing time, films with a fine-grained surface are found, with some randomly distributed large particles bound to this fine-grained surface. Atomic Force Microscopy results indicate an increase of the root-mean-square roughness of CuxS surface with annealing time, from 13.6 up to 37.4 nm, for 255 and 345 s, respectively. The preliminary integration of CuxS films in a TFT bottom-gate type structure allowed the study of the feasibility and compatibility of this material with the remaining stages of a TFT fabrication as well as the determination of the p-type characteristic of the CuxS material. (c) 2013 Elsevier B.V. All rights reserved.

Lavareda, G., A. de Calheiros Velozo, C. Nunes de Carvalho, and A. Amaral. "p/n junction depth control using amorphous silicon as a low temperature dopant source." THIN SOLID FILMS. 543 (2013): 122-124. Abstract

Phosphorus-doped amorphous silicon thin films, deposited at low temperatures by Plasma Enhanced Chemical Vapour Deposition were used as a dopant source on p-type c-Si substrates. A careful step of dehydrogenation was done in order to maintain the a-Si thin-film integrity. Subsequently, a fine-controlled drive-in of dopant, from the amorphous layer to the crystalline wafer was done, to form the p/n junction, using different time periods and temperatures. Dopant profiling in c-Si wafers as well as dopant concentration in a-Si: H films prior to diffusion, both measured by Secondary Ion Mass Spectrometry, are presented. Junction depths obtained are in the range of 98 nm to 2.4 mu m and surface concentrations are in the range of 1.1 x 10(21) to 4.3 x 10(20) at/cm(3). A dual diffusion mechanism explains the ``kink-and-tail{''} shape found for dopant profile. (C) 2013 Elsevier B.V. All rights reserved.

Lavareda, G., A. de Calheiros Velozo, C. Nunes de Carvalho, and A. Amaral. "p/n junction depth control using amorphous silicon as a low temperature dopant source." THIN SOLID FILMS. 543 (2013): 122-124. Abstract

Phosphorus-doped amorphous silicon thin films, deposited at low temperatures by Plasma Enhanced Chemical Vapour Deposition were used as a dopant source on p-type c-Si substrates. A careful step of dehydrogenation was done in order to maintain the a-Si thin-film integrity. Subsequently, a fine-controlled drive-in of dopant, from the amorphous layer to the crystalline wafer was done, to form the p/n junction, using different time periods and temperatures. Dopant profiling in c-Si wafers as well as dopant concentration in a-Si: H films prior to diffusion, both measured by Secondary Ion Mass Spectrometry, are presented. Junction depths obtained are in the range of 98 nm to 2.4 mu m and surface concentrations are in the range of 1.1 x 10(21) to 4.3 x 10(20) at/cm(3). A dual diffusion mechanism explains the ``kink-and-tail{''} shape found for dopant profile. (C) 2013 Elsevier B.V. All rights reserved.

de Calheiros Velozo, A., G. Lavareda, C. Nunes de Carvalho, and A. Amaral. "Thermal dehydrogenation of amorphous silicon: A time-evolution study." THIN SOLID FILMS. 543 (2013): 48-50. Abstract

A model is proposed to describe the decrease of H content in hydrogenated amorphous silicon (a-Si: H), during annealing at a fixed temperature. H content has been measured in several a-Si: H samples ( grown by plasma enhanced chemical vapor deposition) after being submitted to different annealing times at 400 degrees C. Obtained data has been fitted to the proposed model and initial diffusion coefficients of 3.2 x 10(-14) cm(2)/s for intrinsic films and 4.2 x 10(-14) cm(2)/s for n-type films were obtained. Reversely, H content evolution can be predicted during a thermal treatment if diffusion coefficients are previously known. (C) 2013 Elsevier B.V. All rights reserved.

de Calheiros Velozo, A., G. Lavareda, C. Nunes de Carvalho, and A. Amaral. "Thermal dehydrogenation of amorphous silicon: A time-evolution study." THIN SOLID FILMS. 543 (2013): 48-50. Abstract

A model is proposed to describe the decrease of H content in hydrogenated amorphous silicon (a-Si: H), during annealing at a fixed temperature. H content has been measured in several a-Si: H samples ( grown by plasma enhanced chemical vapor deposition) after being submitted to different annealing times at 400 degrees C. Obtained data has been fitted to the proposed model and initial diffusion coefficients of 3.2 x 10(-14) cm(2)/s for intrinsic films and 4.2 x 10(-14) cm(2)/s for n-type films were obtained. Reversely, H content evolution can be predicted during a thermal treatment if diffusion coefficients are previously known. (C) 2013 Elsevier B.V. All rights reserved.

Amaro, P., S. Schlesser, M. Guerra, E. Le Bigot, J. P. Santos, C. I. Szabo, A. Gumberidze, and P. Indelicato. "Absolute measurements and simulations of x-ray line energies of highly charged ions with a double-crystal spectrometer." T156 (2013): 014104. AbstractWebsite
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Amaro, P., S. Schlesser, M. Guerra, E. Le Bigot, J. P. Santos, C. I. Szabo, A. Gumberidze, and P. Indelicato. "Absolute measurements and simulations of x-ray line energies of highly charged ions with a double-crystal spectrometer." Physica Scripta. T156 (2013): 014104. AbstractWebsite
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Szabo, C. I., P. Amaro, M. Guerra, J. P. Santos, A. Gumberidze, J. Attard, and P. Indelicato. "Ion temperature and x-ray line width measurements of highly charged argon ions in an ECR ion source." Physica Scripta. T156 (2013): 014077. AbstractWebsite
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Szabo, C. I., P. Amaro, M. Guerra, J. P. Santos, A. Gumberidze, J. Attard, and P. Indelicato. "Ion temperature and x-ray line width measurements of highly charged argon ions in an ECR ion source." Physica Scripta. T156 (2013): 014077. AbstractWebsite
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Almeida, R. M., P. Turano, I. Moura, J. J. Moura, and S. R. Pauleta. "Superoxide reductase: different interaction modes with its two redox partners." ChemBioChem. 14 (2013): 1858-66. AbstractWebsite

Anaerobic organisms have molecular systems to detoxify reactive oxygen species when transiently exposed to oxygen. One of these systems is superoxide reductase, which reduces O2 (.-) to H2 O2 without production of molecular oxygen. In order to complete the reduction of superoxide anion, superoxide reductase requires an electron, delivered by its redox partners, which in Desulfovibrio gigas are rubredoxin and/or desulforedoxin. In this work, we characterized the interaction of Desulfovibrio gigas superoxide reductase with both electron donors by using steady-state kinetics, 2D NMR titrations, and backbone relaxation measurements. The rubredoxin surface involved in the electron transfer complex with superoxide reductase comprises the solvent-exposed hydrophobic residues in the vicinity of its metal center (Cys9, Gly10, Cys42, Gly43, and Ala44), and a Kd of 3 muM at 59 mM ionic strength was estimated by NMR. The ionic strength dependence of superoxide-mediated rubredoxin oxidation by superoxide reductase has a maximum kapp of (37 +/- 12) min(-1) at 157 mM. Relative to the electron donor desulforedoxin, its complex with superoxide reductase was not detected by chemical shift perturbation, though this protein is able to transfer electrons to superoxide reductase with a maximum kapp of (31 +/- 7) min(-1) at an ionic strength of 57 mM. Competition experiments using steady-state kinetics and NMR spectroscopy (backbone relaxation measurements and use of a paramagnetic relaxation enhancement probe) with Fe-desulforedoxin in the presence of (15) N-Zn-rubredoxin showed that these two electron donors compete for the same site on the enzyme surface, as shown in the model structure of the complex generated by using restrained molecular docking calculations. These combined strategies indicate that the two small electron donors bind in different manners, with the desulforedoxin complex being a short lived electron transfer complex or more dynamic, with many equivalent kinetically competent orientations.

Santos, J. P., J. P. Marques, A. M. Costa, M. C. Martins, P. Indelicato, and F. Parente. "Transition probability values of the 1s 22s3p 3P 0level in Be-like ions." Physica Scripta. T156 (2013): 014020. AbstractWebsite
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Santos, J. P., J. P. Marques, A. M. Costa, M. C. Martins, P. Indelicato, and F. Parente. "Transition probability values of the 1s 22s3p 3P 0level in Be-like ions." Physica Scripta. T156 (2013): 014020. AbstractWebsite
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Miranda, R. M., Telmo G. Santos, J. Gandra, N. Lopes, and R. J. C. Silva. "Reinforcement strategies for producing functionally graded materials by friction stir processing in aluminium alloys." Journal of Materials Processing Technology. 213.9 (2013): 1609-1615. Abstract
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Pinto, Joana V., Rita Branquinho, Pedro Barquinha, Eduardo Alves, Rodrigo Martins, and Elvira Fortunato. "Extended-Gate ISFETs Based on Sputtered Amorphous Oxides." Journal of Display Technology. 9 (2013): 729-734. AbstractWebsite
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Branquinho, Rita, Joana V. Pinto, Tito Busani, Pedro Barquinha, Luis Pereira, Pedro Viana Baptista, Rodrigo Martins, and Elvira Fortunato. "Plastic Compatible Sputtered Ta2O5 Sensitive Layer for Oxide Semiconductor TFT Sensors." Journal of Display Technology. 9 (2013): 723-728. AbstractWebsite
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Sousa, Diogo G., Carla Ferreira, and João M. Lourenço. "Prevenção de Violações de Atomicidade usando Contractos." Proceedings of INForum Simpósio de Informática. INForum 2013. Lisbon, Portugal: Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa, 2013. 190-201. Abstractinforum2013-sousa.pdf

A programação concorrente obriga o programador a sincronizar os acessos concorrentes a regiões de memória partilhada, contudo esta abordagem não é suficiente para evitar todas as anomalias que podem ocorrer num cenário concorrente. Executar uma sequência de operações atómicas pode causar violações de atomicidade se existir uma correlação entre essas operações, devendo o programador garantir que toda a sequência de operações é executada atomicamente. Este problema é especialmente comum quando se usam operações de pacotes ou módulos de terceiros, pois o programador pode identificar incorretamente o âmbito das regiões de código que precisam de ser atómicas para garantir o correto comportamento do programa. Para evitar este problema o programador do módulo pode criar um contrato que especifica quais as sequências de operações do módulo que devem ser sempre executadas de forma atómica. Este trabalho apresenta uma análise estática para verificação destes contratos.