Institute Ciencia E Engineering Of Materiais E Superficies

Lisbon, Portugal

Institute Ciencia E Engineering Of Materiais E Superficies

Lisbon, Portugal
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Santos I.C.T.,University of Porto | Rodrigues A.,University of Lisbon | Figueiredo L.,Institute Ciencia E Engineering Of Materiais E Superficies | Rocha L.A.,University of Minho | Tavares J.M.R.S.,University of Porto
Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications | Year: 2012

An aneurysm is a localized blood-filled dilatation of an artery whose consequences can be deadly. One of its current treatments is endovascular aneurysm repair, a minimally invasive procedure in which an endoprosthesis, called a stent-graft, is placed transluminally to prevent wall rupture. Early stent-grafts were custom designed for the patient through the assembling of off-the-shelf components by the operating surgeon. However, nowadays, stent-grafts have become a commercial product. The existing endoprostheses differ in several aspects, such as shape design and materials, but they have in common a metallic scaffold with a polymeric covering membrane. This article aims to gather relevant information for those who wish to understand the principles of stent-grafts and even to develop new devices. Hence, a stent-graft classification based on different characteristics is presented and the desired features for an ideal device are pointed out. Additionally, the materials currently in use to fabricate this type of endoprosthesis are reviewed and new materials are suggested. © IMechE 2012 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.


Fortes L.M.,Institute Ciencia E Engineering Of Materiais E Superficies | Goncalves M.C.,University of Lisbon | Goncalves M.C.,Institute Ciencia E Engineering Of Materiais E Superficies | Pereira J.C.,University of Lisbon | D'Acapito F.,CNR Institute of Materials
Journal of Non-Crystalline Solids | Year: 2014

Hollow and dense SiO2 microspheres doped with Er,Yb were characterized by extended X-ray absorption fine structure (EXAFS) on the Er,Yb LIII edges and photoluminescence (PL) measurements. The samples were synthesized by the sol-gel method and in situ Er,Yb doped, by introducing fluoride compounds (ErF3, YbF3) in the sol. Er,Yb doped transparent glass-ceramic, formed by NaYF4 nanocrystals dispersed in SiO2 matrix, was taken as the reference. The EXAFS results illustrate the Er,Yb local environment in all studied SiO2 matrices: in hollow-microspheres, crystalline Er,Yb fluoride was formed while in dense-microspheres, crystalline Er,Yb oxide developed. PL measurements of the Er3 + emission at 1.54 μm were performed, on hollow and dense SiO2 microspheres, for different Er3 +/Yb3 + ratios, ranging from 1:3 to 1:10 mol%. Upconversion was observed in all samples, ordered by efficiency for the studied Er,Yb environments as: glass-ceramic (NaYF4 environment) ≪ hollow SiO2 microspheres (Er,Yb fluoride crystalline environment) > dense SiO2 microspheres (Er,Yb oxide crystalline environment). X-ray excited optical luminescence (XEOL) confirmed the Er green upconversion results. © 2014 Published by Elsevier B.V.


Oliveira V.,Polytechnic Institute of Lisbon | Oliveira V.,Institute Ciencia E Engineering Of Materiais E Superficies | Nunes B.,University of Lisbon | Vilar R.,University of Lisbon | Vilar R.,Institute Ciencia E Engineering Of Materiais E Superficies
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2010

The wettability of polyimide surfaces microstructured using KrF laser radiation at fluences above the material ablation threshold was studied by static contact angle measurements. The laser-treated surfaces present a morphology consisting of conical features whose dimensions and areal density depend on the fluence. The effect of these parameters on the surface apparent contact angle depends on the wetting regime. When wetting occurs in the homogeneous regime, the apparent contact angle of the treated surfaces increases with the radiation fluence because the cone dimensions increase. In contrast, when wetting occurs in the heterogeneous regime, the apparent contact angle increases with the radiation fluence because the average distance between cones increases. The apparent water contact angle of the laser-treated surfaces can reach values as high as 162°, as compared to 75° for virgin polyimide. © 2010 Elsevier B.V. All rights reserved.


Goncalves M.C.,University of Lisbon | Goncalves M.C.,Institute Ciencia E Engineering Of Materiais E Superficies | Fortes L.M.,Institute Ciencia E Engineering Of Materiais E Superficies | Pimenta A.R.,University of Lisbon | And 8 more authors.
Current Nanoscience | Year: 2013

In the present work, magnetic nanoparticles coated with silica or ORMOSIL are prepared in a two step process. In the first step, SPIONs with 6 nm average diameter are produced by a reduction-precipitation process conducted in air and in the second one, SPIONs were used as seeds for silica/ORMOSIL growth (below 30 nm), in situ by a modified Stöber sol-gel method. SPIONs and silica/ ORMOSIL magnetic core-shell nanostructures were characterized by X-Ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), Mössbauer spectroscopy and SQUID magnetometry. TEM observations of SPIONs and silica/ORMOSIL SPIONs allow determining size and shape. FTIR allows determining silica/ORMOSIL structural fingerprints. X-ray and Mössbauer spectroscopy allow determining the magnetite/maghemite ratio, discussed as a nanosized constrained. SPIONs and silica/ORMOSIL SPIONs show superparamagnetic properties making them appropriated to biomedical applications. © 2013 Bentham Science Publishers.


Colaco R.,University of Lisbon | Goncalves M.C.,University of Lisbon | Goncalves M.C.,Institute Ciencia E Engineering Of Materiais E Superficies | Fortes L.M.,Institute Ciencia E Engineering Of Materiais E Superficies | And 3 more authors.
Current Nanoscience | Year: 2013

One focus in nanotechnology is the development and use of nonviral vectors for safe and efficient gene delivery. Inorganic and organically modified silica nanoparticles are chemical and biologically inert, optically transparent and can be doped with imaging agents and/or functionalized to promote its conjugation with different therapeutic molecules. Silica/ORMOSIL nanoparticles can be engineered to improve diagnosis, treatment and follow-up of diseases. A combination of diagnosis devices and therapeutics (theranostics) would be beneficial for patients. In this work, ORMOSIL nanoparticles as non-viral vectors for gene delivery were prepared via a modified Stober sol-gel process directly with 3-aminopropyltriethoxysilane (APTES), methyltriethoxysilane (MTES), vinyltrimethoxysilane (VTES), N1-[3-(trimethoxysilyl)-propyl]diethylenetriamine (DETA), and tetraethylorthosilicate (TEOS) as precursors. Dynamic light scattering, transmission electron microscopy and Fourier transformed infrared spectroscopy were used to characterize the ORMOSIL nanospheres. Synthesis has been optimized and monodisperse spherical nanoparticles with desired size have been obtained. Nanoparticle-DNA complexes were successfully obtained at different ratios (nanoparticle/pDNA) and confirmed by agarose gel electrophoresis and ethidium bromide exclusion test. © 2013 Bentham Science Publishers.


Cunha A.,Institute Ciencia E Engineering Of Materiais E Superficies | Cunha A.,University of Lisbon | Cunha A.,University of Bordeaux 1 | Serro A.P.,University of Lisbon | And 8 more authors.
Applied Surface Science | Year: 2013

The aim of the present work was to investigate the wetting behaviour of biomedical grade Ti-6Al-4V alloy surfaces textured by a femtosecond laser treatment. The material was treated in ambient atmosphere using an Yb: KYW chirped-pulse-regenerative amplification laser with a wavelength of 1030 nm and a pulse duration of 500 fs. Four main types of surface textures were obtained depending on the processing parameters and laser treatment method. These textures consist of: (1) nanoscale laser-induced periodic surface structures (LIPSS); (2) nanopillars; (3) a bimodal roughness distribution texture formed of LIPSS overlapping microcolumns; (4) a complex texture formed of LIPSS overlapping microcolumns with a periodic variation of the columns size in the laser scanning direction. The wettability of the surfaces was evaluated by the sessile drop method using distilled-deionized (DD) water and Hank's balanced salt solution (HBSS) as testing liquids. The laser treated surfaces present a hydrophilic behaviour as well as a high affinity for the saline solution, with equilibrium contact angles in the ranges 24.1-76.2°for DD water and 8.4-61.8°for HBSS. The wetting behaviour is anisotropic, reflecting the anisotropy of the surface textures. © 2012 Elsevier B.V. All rights reserved.


Oliveira V.,Polytechnic Institute of Lisbon | Oliveira V.,Institute Ciencia E Engineering Of Materiais E Superficies | Polushkin N.I.,University of Lisbon | Polushkin N.I.,Institute Ciencia E Engineering Of Materiais E Superficies | And 4 more authors.
Optics and Laser Technology | Year: 2012

We report on a simple method to obtain surface gratings using a Michelson interferometer and femtosecond laser radiation. In the optical setup used, two parallel laser beams are generated using a beam splitter and then focused using the same focusing lens. An interference pattern is created in the focal plane of the focusing lens, which can be used to pattern the surface of materials. The main advantage of this method is that the optical paths difference of the interfering beams is independent of the distance between the beams. As a result, the fringes period can be varied without a need for major realignment of the optical system and the time coincidence between the interfering beams can be easily monitored. The potential of the method was demonstrated by patterning surface gratings with different periods on titanium surfaces in air. © 2012 Elsevier Ltd.


Alves S.,University of Lisbon | Alves S.,Institute Ciencia E Engineering Of Materiais E Superficies | Oliveira V.,Institute Ciencia E Engineering Of Materiais E Superficies | Oliveira V.,Polytechnic Institute of Lisbon | And 2 more authors.
Journal of Physics D: Applied Physics | Year: 2012

The surface morphology, structure and composition of human dentin treated with a femtosecond infrared laser (pulse duration 500fs, wavelength 1030nm, fluences ranging from 1 to 3Jcm 2) was studied by scanning electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The average dentin ablation threshold under these conditions was 0.6±0.2Jcm 2 and the ablation rate achieved in the range 1 to 2μm/pulse for an average fluence of 3Jcm 2. The ablation surfaces present an irregular and rugged appearance, with no significant traces of melting, deformation, cracking or carbonization. The smear layer was entirely removed by the laser treatment. For fluences only slightly higher than the ablation threshold the morphology of the laser-treated surfaces was very similar to the dentin fracture surfaces and the dentinal tubules remained open. For higher fluences, the surface was more porous and the dentin structure was partially concealed by ablation debris and a few resolidified droplets. Independently on the laser processing parameters and laser processing method used no sub-superficial cracking was observed. The dentin constitution and chemical composition was not significantly modified by the laser treatment in the processing parameter range used. In particular, the organic matter is not preferentially removed from the surface and no traces of high temperature phosphates, such as the β-tricalcium phosphate, were observed. The achieved results are compatible with an electrostatic ablation mechanism. In conclusion, the high beam quality and short pulse duration of the ultrafast laser used should allow the accurate preparation of cavities, with negligible damage of the underlying material. © 2012 IOP Publishing Ltd.


Polushkin N.I.,University of Lisbon | Polushkin N.I.,Institute Ciencia E Engineering Of Materiais E Superficies | Duarte A.C.,University of Lisbon | Duarte A.C.,Institute Ciencia E Engineering Of Materiais E Superficies | And 12 more authors.
Applied Surface Science | Year: 2015

We investigate the origin of ferromagnetism induced in thin-film (∼20 nm) Fe-V alloys by their irradiation with subpicosecond laser pulses. We find with Rutherford backscattering that the magnetic modifications follow a thermally stimulated process of diffusion decomposition, with formation of a-few-nm-thick Fe enriched layer inside the film. Surprisingly, similar transformations in the samples were also found after their long-time (∼103 s) thermal annealing. However, the laser action provides much higher diffusion coefficients (∼4 orders of magnitude) than those obtained under standard heat treatments. We get a hint that this ultrafast diffusion decomposition occurs in the metallic glassy state achievable in laser-quenched samples. This vitrification is thought to be a prerequisite for the laser-induced onset of ferromagnetism that we observe. © 2014 Elsevier B.V. All rights reserved.

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