Export 2389 results:
Sort by: Author Title Type [ Year  (Desc)]
2013
Santos, R., J. Loureiro, A. Nogueira, E. Elangovan, JV Pinto, JP Veiga, T. Busani, E. Fortunato, R. Martins, and I. Ferreira. "Thermoelectric properties of V2O5 thin films deposited by thermal evaporation." Applied Surface Science. 282 (2013): 590-594. Abstract
n/a
Santos, R., J. Loureiro, A. Nogueira, E. Elangovan, JV Pinto, JP Veiga, T. Busani, E. Fortunato, R. Martins, and I. Ferreira. "Thermoelectric properties of V< sub> 2 O< sub> 5 thin films deposited by thermal evaporation." Applied Surface Science (2013). Abstract
n/a
Santos, R., J. Loureiro, A. Nogueira, E. Elangovan, JV Pinto, JP Veiga, T. Busani, E. Fortunato, R. Martins, and I. Ferreira. "Thermoelectric properties of V< sub> 2 O< sub> 5 thin films deposited by thermal evaporation." Applied Surface Science. 282 (2013): 590-594. Abstract
n/a
Geng, Yong, Pedro L. Almeida, Gabriel M. Feio, João L. Figueirinhas, and Maria H. Godinho. "Water-based cellulose liquid crystal system investigated by Rheo-NMR." Macromolecules. 46.11 (2013): 4296-4302. Abstract
n/a
Teixeira, Paulo, Susete N. Fernandes, João Canejo, Maria Helena Godinho, Catarina Leal, and Loic Hilliou. "When Liquid Crystalline Cellulose Flows and Relaxes." Ibereo 2013 (2013). Abstract
n/a
Figueiredo, Ondina M., Teresa Pereira Silva, João Pedro Veiga, Daniel PS Oliveira, and Maria João Batista. "X-ray absorption spectroscopy at Re L3-edge applied to mine waste materials: a possible input to the sustainable recovery of rhenium." 2nd Meeting of Synchrotron Radiation Users from Portugal and ESRF-Day. 2013. Abstract
n/a
Nandy, Suman, Gonçalo Gonçalves, Joana Vaz Pinto, Tito Busani, Vitor Figueiredo, Lu\'ıs Pereira, Rodrigo Ferrão {Paiva Martins}, and Elvira Fortunato. "{Current transport mechanism at metal-semiconductor nanoscale interfaces based on ultrahigh density arrays of p-type NiO nano-pillars.}." Nanoscale. 5 (2013): 11699-709. AbstractWebsite

The present work focuses on a qualitative analysis of localised I-V characteristics based on the nanostructure morphology of highly dense arrays of p-type NiO nano-pillars (NiO-NPs). Vertically aligned NiO-NPs have been grown on different substrates by using a glancing angle deposition (GLAD) technique. The preferred orientation of as grown NiO-NPs was controlled by the deposition pressure. The NiO-NPs displayed a polar surface with a microscopic dipole moment along the (111) plane (Tasker's type III). Consequently, the crystal plane dependent surface electron accumulation layer and the lattice disorder at the grain boundary interface showed a non-uniform current distribution throughout the sample surface, demonstrated by a conducting AFM technique (c-AFM). The variation in I-V for different points in a single current distribution grain (CD-grain) has been attributed to the variation of Schottky barrier height (SBH) at the metal-semiconductor (M-S) interface. Furthermore, we observed that the strain produced during the NiO-NPs growth can modulate the SBH. Inbound strain acts as an external field to influence the local electric field at the M-S interface causing a variation in SBH with the NPs orientation. This paper shows that vertical arrays of NiO-NPs are potential candidates for nanoscale devices because they have a great impact on the local current transport mechanism due to its nanostructure morphology.

Pinto, Joana V., Rita Branquinho, Pedro Barquinha, Eduardo Alves, Rodrigo Martins, and Elvira Fortunato. "{Extended-gate ISFETs based on sputtered amorphous oxides}." IEEE/OSA Journal of Display Technology. 9 (2013): 729-734. Abstract

We present the results obtained with an extended-gate ISFET totally based on amorphous oxides (GIZO as the semiconductor, {\textless}formula formulatype="inline"{\textgreater}{\textless}tex Notation="TeX"{\textgreater}{\$}{\{}hbox{\{}Ta{\}}{\}}{\_}{\{}2{\}}{\{}hbox{\{}O{\}}{\}}{\_}{\{}5{\}}{\{}hbox{\{}:SiO{\}}{\}}{\_}{\{}2{\}}{\$}{\textless}/tex{\textgreater} {\textless}/formula{\textgreater} as the dielectric and {\textless}formula formulatype="inline"{\textgreater}{\textless}tex Notation="TeX"{\textgreater}{\$}{\{}hbox{\{}Ta{\}}{\}}{\_}{\{}2{\}}{\{}hbox{\{}O{\}}{\}}{\_}{\{}5{\}}{\$}{\textless}/tex{\textgreater} {\textless}/formula{\textgreater} as the sensitive layer). A full characterization of the device was performed with constant ionic strength pH buffer solutions, revealing a sensitivity of 40 mV/pH with small hysteresis, and good linearity in the pH 4{&}{\#}x2013;pH 10 range buffer solutions. These results clearly show that it is possible to produce room-temperature disposable and low cost bio-sensors.

Cruz, M. M., R. C. Silva, JV Pinto, R. P. Borges, N. Franco, and A. Casaca. "{Formation of oriented nickel aggregates in rutile single crystals by Ni implantation}." Journal of Magnetism and Magnetic Materials. 340 (2013): 102-108. AbstractWebsite

The magnetic and electrical properties of Ni implanted single crystalline TiO2 rutile were studied for nominal implanted fluences between 0.5?1017 cm−2 and 2.0?1017 cm−2 with 150 keV energy, corre- sponding to maximum atomic concentrations between 9 at{%} and 27 at{%} at 65 nm depth, in order to study the formation of metallic oriented aggregates. The results indicate that the as implanted crystals exhibit superparamagnetic behavior for the two higher fluences, which is attributed to the formation of nanosized nickel clusters with an average size related with the implanted concentration, while only paramagnetic behavior is observed for the lowest fluence. Annealing at 1073 K induces the aggregation of the implanted nickel and enhances the magnetization in all samples. The associated anisotropic behavior indicates preferred orientations of the nickel aggregates in the rutile lattice consistent with Rutherford backscattering spectrometry—channelling results. Electrical conductivity displays anisotropic behavior but no magnetoresistive effects were detected.

Alves, Raquel D., Lu\'ısa C. Rodrigues, Juliana R. Andrade, Mariana Fernandes, Joana V. Pinto, Lu\'ıs Pereira, Agnieszka Pawlicka, Rodrigo Martins, Elvira Fortunato, Verónica {de Zea Bermudez}, and Maria Manuela Silva. "{Gelatin n Zn(CF 3 SO 3 ) 2 Polymer Electrolytes for Electrochromic Devices}." Electroanalysis. 25 (2013): 1483-1490. AbstractWebsite
n/a
Figueiredo, V., JV Pinto, J. Deuermeier, R. Barros, E. Alves, R. Martins, and E. Fortunato. "{p-Type Cu O Thin-Film Transistors Produced by Thermal Oxidation}." Journal of Display Technology. 9 (2013): 735-740. Abstract

Thin-films of copper oxide Cu O were produced by thermal oxidation of metallic copper (Cu) at different tempera- tures (150–450 C). The films produced at temperatures of 200, 250 and 300 C showed high Hall motilities of 2.2, 1.9 and 1.6 cm V s , respectively. Single Cu O phases were obtained at 200 Cand its conversion toCuO starts at 250 C. For lower thick- nesses 40 nm, the films oxidized at 250 Cshowed a complete conversion to CuO phase. Successful thin-film transistors (TFTs) were produce by thermal oxidation of a 20 nm Cu film, obtaining p-type Cu O (at 200 C) and CuO (at 250 C) with On/Off ratios of 6 10 and 1 10 , respectively.

Parthiban, Shanmugam, Elamurugu Elangovan, Pradipta K. Nayak, Alexandra Gonçalves, Daniela Nunes, Lu\'ıs Pereira, Pedro Barquinha, Tito Busani, Elvira Fortunato, and Rodrigo Martins. "{Performances of Microcrystalline Zinc Tin Oxide Thin-Film Transistors Processed by Spray Pyrolysis}." 9 (2013): 825-831. Abstract
n/a
Branquinho, Rita, Joana V. Pinto, Tito Busani, Pedro Barquinha, Luis Pereira, Pedro Viana Baptista, Rodrigo Martins, and Elvira Fortunato. "{Plastic Compatible Sputtered Ta O Sensitive Layer for Oxide Semiconductor TFT Sensors}." 9 (2013): 723-728. Abstract
n/a
Branquinho, Rita, Joana V. Pinto, Tito Busani, Pedro Barquinha, Luis Pereira, Pedro Viana Baptista, Rodrigo Martins, and Elvira Fortunato. "{Plastic Compatible Sputtered Ta O Sensitive Layer for Oxide Semiconductor TFT Sensors}." Journal of Display Technology. 9 (2013): 723-728. Abstract

The effect of post-deposition annealing temperature on the pH sensitivity of room temperature RF sputtered Ta O was investigated. Structural and morphological features of these films were analyzed before and after annealing at various tem- peratures. The deposited films are amorphous up to 600 Cand crystallize at 700 C in an orthorhombic phase. Electrolyte-insu- lator-semiconductor (EIS) field effect based sensors with an amor- phousTa O sensing layer showed pHsensitivity above 50 mV/pH. For sensors annealed above 200 C pH sensitivity decreased with increasing temperature. Stabilized sensor response andmaximum pHsensitivitywas achieved after low temperature annealing at 200 C, which is compatible with the use of polymeric substrates and application as sensitive layer in oxides TFT-based sensors

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}." IEEE/OSA Journal of Display Technology. 9 (2013): 723-728. AbstractWebsite

The effect of post-deposition annealing temperature on the pH sensitivity of room temperature RF sputtered Ta2O5 was investigated. Structural and morphological features of these films were analyzed before and after annealing at various temperatures. The deposited films are amorphous up to 600 °C and crystallize at 700 °C in an orthorhombic phase. Electrolyte-insulator-semiconductor (EIS) field effect based sensors with an amorphous Ta2O5 sensing layer showed pH sensitivity above 50 mV/pH. For sensors annealed above 200 °C pH sensitivity decreased with increasing temperature. Stabilized sensor response and maximum pH sensitivity was achieved after low temperature annealing at 200 °C, which is compatible with the use of polymeric substrates and application as sensitive layer in oxides TFT-based sensors.

Fernandes-Silva, S., J. Moreira-Silva, T. H. Silva, R. I. Perez-Martin, C. G. Sotelo, J. F. Mano, A. R. C. Duarte, and R. L. Reis. "{Porous hydrogels from shark skin collagen crosslinked under dense carbon dioxide atmosphere}." Macromolecular Bioscience. 13 (2013). Abstract

The possibility to fabricate marine collagen porous structures crosslinked with genipin under high pressure carbon dioxide is investigated. Collagen from shark skin is used to prepare pre-scaffolds by freeze-drying. The poor stability of the structures and low mechanical properties require crosslinking of the structures. Under dense CO 2 atmosphere, crosslinking of collagen pre-scaffolds is allowed for 16 h. Additionally, the hydrogels are foamed and the scaffolds obtained present a highly porous structure. In vitro cell culture tests performed with a chondrocyte-like cell line show good cell adherence and proliferation, which is a strong indication of the potential of these scaffolds to be used in tissue cartilage tissue engineering. The development of an optimized processing technique for the preparation of stable structures from marine origin collagen is described. The samples are processed under a dense carbon dioxide atmosphere that promotes crosslinking and enhances the morphology of the 3D architectures obtained. © 2013 WILEY-VCH Verlag GmbH {&} Co. KGaA, Weinheim.

a.M. Ramos, S. Pereira, M. T. Cidade, G. Pereira, R. Branquinho, L. Pereira, R. Martins, and E. Fortunato. "{Preparation and characterization of cellulose nanocomposite hydrogels as functional electrolytes}." Solid State Ionics. 242 (2013): 26-32. AbstractWebsite
n/a
Ramos, A. M., S. Pereira, M. T. Cidade, G. Pereira, R. Branquinho, L. Pereira, R. Martins, and E. Fortunato. "{Preparation and characterization of cellulose nanocomposite hydrogels as functional electrolytes}." Solid State Ionics. 242 (2013): 26-32. AbstractWebsite

In this work Laponite was combined with a modified abundant natural polymer, (caboxymethyl cellulose), acrylic sodium salt polymer and lithium perchlorate aiming to produce inexpensive and sustainable nanocomposite electrolytes for functional electrochemical devices. Optical, electrochemical, structural, morphological and rheological characterization was performed in order to evaluate their properties and potential advantages as electrolyte. It was verified that the addition of Laponite led to an ionic conductivity at room temperature (25 C) in the range of 6 to 9 ?? 10- 5 Scm - 1 this value being then determined by the composition of the nanocomposite. These electrolytes were applied to electrochromic devices using evaporated nickel oxide thin film as the electrochromic layer. The devices exhibited a significant transmittance modulation that exceeds 45 {%} at 600 nm. ?? 2013 Elsevier B.V.

Engineering, Tissue, Cell Based, Campus D. E. Gualtar, Maria Manuela, Estima Gomes, A. N. A. Rita, Cruz Duarte, Sentido D. E. Fornecer, U. M. A. Estrutura, Porosa E. Interconectada, and Suporte D. E. A. O. Crescimento. "{PT 106220}." 106220 (2013). Abstract
n/a
Engineering, Tissue, Cell Based, Campus D. E. Gualtar, Maria Manuela, Estima Gomes, A. N. A. Rita, Cruz Duarte, Sentido D. E. Fornecer, U. M. A. Estrutura, Porosa E. Interconectada, and Suporte D. E. A. O. Crescimento. "{PT 106220}." 106220 (2013). Abstract
n/a
Machado, J., A. Blanco, P. Fonte, D. Galaviz, L. Lopes, Ferreira R. Marques, and P. Teubig. "{Simulations of a new detection concept for high-energy neutrons based on timing RPCs}." Journal of Instrumentation. 8 (2013): P07020. AbstractWebsite
n/a
Alves, R. D., L. C. Rodrigues, J. R. Andrade, A. Pawlicka, L. Pereira, R. Martins, E. Fortunato, and M. M. Silva. "{Study and Characterization of a Novel Polymer Electrolyte Based on Agar Doped with Magnesium Triflate}." Molecular Crystals and Liquid Crystals. 570 (2013): 1-11. AbstractWebsite
n/a
2012
Vitor Rosa, Sara Realista, Ana Mourato, Luisa Maria Abrantes, Joao Henriques, Maria Jose Calhorda, Teresa Aviles, Michael G. B. Drew, and Vitor Felix. "{1,1 `-Bis(diphenylphosphino)ferrocene bridging two mono(cyclopentadienyl) cobalt moieties: Synthesis, structure, electrochemistry and DFT studies}." {JOURNAL OF ORGANOMETALLIC CHEMISTRY}. {712} (2012): {52-56}. Abstract

{Reaction of {[}Co(eta(5)-C5H5)(CO)(2)], 1, with 1,1'-bis(diphenylphosphino)ferrocene (dppf) yields the new trinuclear complex {[}Co(eta(5)-C5H5)(CO)](2)(mu-dppf), 2, which was structurally characterised by single crystal X-ray diffraction and showed two Co(eta(5)-C5H5)(CO) moieties covalently linked by a dppf bridge. Electrochemical studies in dichloromethane revealed that both Co(I) and Fe(II) in the precursors were oxidized to Co(II)/Co(III) and Fe(III), respectively. On the other hand, in 2 the two first oxidation waves were assigned to Co, the Fe(II) centre requiring a higher potential than in free dppf. DFT calculations showed that the HOMOs of 2 were localised in the Co fragments, owing to the destabilisation of the Co(eta(5)-C5H5)(CO) orbitals after binding dppf. (C) 2012 Elsevier B.V. All rights reserved.}

Monteiro, Regina C. C., Andreia A. S. Lopes, Maria M. A. Lima, Joao P. Veiga, Rui JC Silva, Carlos J. Dias, Erika J. R. Davim, and Maria H. V. Fernandes. "Sintering, Crystallization, and Dielectric Behavior of Barium Zinc Borosilicate GlassesuEffect of Barium Oxide Substitution for Zinc Oxide." Journal of the American Ceramic Society. 95.10 (2012): 3144-3150. Abstract
n/a
Amaro, P., F. Fratini, S. Fritzsche, P. Indelicato, J. P. Santos, and A. Surzhykov. "Parametrization of the angular correlation and degree of linear polarization in two-photon decays of hydrogenlike ions." Phys. Rev. A. 86 (2012): 042509. AbstractWebsite

The spontaneous two-photon emission in hydrogenlike ions is investigated within the framework of second- order perturbation theory and Dirac’s equation. Special attention is paid to the angular correlation of the emitted photons as well as to the degree of linear polarization of one of the two photons, if the second is just observed under arbitrary angles. Expressions for the angular correlation and the degree of linear polarization are expanded in powers of cosine functions of the two-photon opening angle, whose coefficients depend on the atomic number and the energy sharing of the emitted photons. The effects of including higher (electric and magnetic) multipoles upon the emitted photon pairs beyond the electric-dipole approximation are also discussed. Calculations of the coefficients are performed for the transitions 2s1/2 → 1s1/2, 3d3/2 → 1s1/2, and 3d5/2 → 1s1/2, along the entire hydrogen isoelectronic sequence (1