J.A.T. Borges da Costa

Ion beam analysis of plasma nitrided Ti6Al4V-ELI

Abstract Nitrogen and aluminum concentration profiles in the near surface region of the Ti6Al4V-ELI alloy plasma nitrided under controlled processing conditions are studied by nuclear reactions analysis (NRA). The results are complemented by compound identification using grazing angle X-ray diffraction (GXRD) and visual inspection of the microstructure by backscattered electron (BSE) scanning microscopy. The layered structure of titanium nitrides near the surface of the alloy is described as a function of the nitriding temperature and the adequacy of the NRA technique is discussed.

Pulsed-dye laser treatment of Jessner lymphocytic infiltration of the skin

© 2008 The Authors JEADV 2009, 23, 570–620 Journal compilation

Extra-facial melasma: clinical, histopathological, and immunohistochemical case-control study

Background  Extra‐facial melasma is a prevalent dermatosis in some populations with special characteristics in relation to its clinical aspects and probable etiopathogenic factors. Few studies have attempted to address this alteration of pigmentation, which has become a challenge in clinical Dermatology.

Comment on ‘‘Ion mixing of metal/Al bilayers near 77 K’’ [Appl. Phys. Lett. 54, 413 (1989)]

The correct mixing efficiency for the Fe/Al bilayer (900 keV Xe +3 , 77K) is presented in the context of the recent analysis by Ma, IE.E., Work man, W.L>, Johnson, W.L., and Nicolet, M.A. (AIP)

Sexually transmitted infections and related sociodemographic factors in Lisbon's major Venereology Clinic: a descriptive study of the first 4 months of 2007.

Objectives  To assess the prevalence of sexually transmitted infections (STI) and relationships between them and sociodemographic/behavioural data in the major Venereology Clinic in Lisbon.

Color Mathematical Morphology Based on Partial Ordering of Spectra

Mathematical morphology is based on the principle of ordering. There is no natural way to order colors (being triplets of scalars). A lot of different ordering relations have been proposed in the literature, most on an ad-hoc basis. In this paper, we propose an ordering relation for colors that is based on the natural (i.e. physically plausible) ordering of spectra. Therefore, we ensure that the ordering is independent of the chosen color parameterization. We discuss that part of colorimetric theory that enables us to reconstruct the spectrum given the three color parameters. Furthermore, we present the very basics of the algebraic framework of mathematical morphology. This allows us to embed the presented ordering of colors within the morphological framework such that we can fully exploit the possibilities to define morphological image operators working on color images.

Improvement of precision for pipetting blood serum samples into a graphite furnace

Abstract Graphite furnace atomic absorption spectrometry is a well-established technique for trace metal determination in blood and serum samples. For this kind of samples, a R.S.D. of up to 10% is considered acceptable, especially for those elements, the concentrations of which do not allow high dilution. Among the reasons that contribute to an increase of the S.D. is the retention of proteins (and analyte) in the sample dispenser capillary, because proteins might be adsorbed on polymeric surfaces. In the present work, the interaction protein/polymer was studied, considering the amount of protein that could be retained by the capillary, the influence of sample dilution, time of contact and the possible co-adsorption of metals. Serum proteins were retained in the capillary, depending on the material (Tygon>silicone rubber>poly(tetrafluorethylene)); dilution did not prevent the adsorption, and only 30 s of contact were enough for the adsorption to occur. Using a column filled with PTFE powder (60 mesh), it was possible to observe that metals were co-adsorbed to a large extent. Water, diluted nitric acid or aqueous solutions of Triton X-100 were not able to promote the complete desorption of the proteins retained by the polymeric materials. Total elution was achieved with methanol, and its use as rinse solution decreased the R.S.D. (n=10) for aluminium, manganese and chromium determination in serum to

A Mössbauer study on the ion-beam-induced phases in the Fe/Al thin film bilayer

Conversion Electron Mössbauer Spectroscopy, (CEMS), has been used to study ion-beam-induced mass transport and phase formation in the Fe/Al bilayer system. In a previous work it was shown that ion irradiation in the same system with noble gases (Ar+, Kr2+, and Xe3+) leaded to the formation of non intermetallic phases when the samples were kept at 77 and 300 K during the bombardments. On the other hand, intermetallic phases were observed for irradiations at substrate temperature of 500 K. The last experimental condition for phase formation corresponds to a lower temperature than conventional thermal treatment needs to reach the same phase. Here, the irradiation conditions were devised to account intermediate substrate temperatures, namely 200 and 400 K, in order to identify the effect of the implantation dose in the phase formation. The intermetallic phases observed in the samples submitted to irradiations at substrate temperature of 500 K, are now formed by even lower temperature-400 K. The results also show a threshold dose of irradiation above which the intermetallic phases are formed. These observations are discussed in terms of a superposition of collision cascades.

SURFACE METALLURGY WITH HIGH ENERGY HEAVY ION BEAMS

High energy noble gas ion beams are currently used to induce the formation of specific surface alloys from vacuum deposited multilayered thin film structures on metallic or insulating engineering components. We discuss in this paper the formation of metastable and stable, amorphous and crystalline phases by ion beam mixing. In particular we discuss the intermetallic compounds of the Fe-Al thin film bilayer system formed on the surface of insulating substrates by means of high vacuum furnace annealing, ion bombardment of the bilayer interface and the simultaneous combination of these two metallurgical treatments.

Depth dependence of electrical resistivity transformations by ion beams

Abstract In situ electrical resistivity of thin-film β-NiAl under Ar irradiation at 77 K has been measured as a function of the total fluence for different film thickness in order to investigate the depth dependence of ion beam induced transformations. Results are interpreted according to a simple phenomenological model that includes depth-dependent effects through variable cross sections for specific transformations. It is shown that inclusion of such dependence accounts for the observed variation of electrical behaviours under irradiation not predicted by the standard kinetic models.