Developing methods for immobilizing metallic nanoparticles (NP) onto different surfaces is a subject of fundamental interest, as nanometric structures enable the appearance of novel properties, absent in bulk or even in micrometric dimensions. In fact, the presence of NP with different size and shape on surfaces can induce substantial modifications on their electronic, optical, magnetic, physical or chemical proprieties. This will be very useful for many applications in different areas ranging from electronics to biomedicine.

In this work, we use a simple, reproducible and economic method to grow metallic gold and silver NP directly on cellulose surfaces. A prior chemical activation of the alcohol groups on the cellulose surface is needed for grafting amino functions, which will complex silver and gold ions. Therefore, NP nucleation is only allowed and selectively accomplished on these seed coordination sites. The growth of NP is achieved by the interaction of aqueous dilute solutions of AgNO3 or NaAuCl4 with the cellulose surface. The procedure limits the generation of NP only to the cellulose surface, keeping the dispersion medium completely exempt of them. The resulting NP are, consequently chemically immobilized on the cellulose surface. The chemical anchoring of the NP to the surface avoids particle desorption and extends the lifetime of the resulting hybrid materials. Following this procedure, silver and gold NP could be successfully created on cellulose and this was supported by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM).

The present AFM (Figure 1) study enabled to characterize the size and shape of silver NP: they are spherical and have a diameter of ~15 nm. SEM image of Ag NP (Figure 2) display the existence of NP agglomerates. Comparison of the two images suggests size and spatial distributions strongly non- uniform. It is now a challenge to deposit nanoparticles in an organized manner, achieving a regular surface functionalization of cellulose. In TEM (Figure 3) we see a sample where Ag and Au salts interacted simultaneously with the cellulose surface. Crossing the images with other information from analytical techniques, it seems that Ag NP and Au NP form mainly separately instead of presenting a core-shell structure. Also, there is evidence that larger NP are the ones made of silver which suggests that the final result is kinetically (and not thermodynamically) controlled.

The authors acknowledge FCT for A.M. Ferraria Grant SFRH/BPD/26239/2006, for A. P. Carapeto Grant SFRH/BD/75734/2011 and strategic projects PEst-OE/CTM/LA0024/2011 and PEst-OE/CTM-UI0084/2011.

Dispersing nanodiamond (nD) particles in metallic matrices can be achieved by ball milling resulting in metal-diamond composite powders. The matrices have been selected considering the whole range of carbon affinity: copper that shows extremely reduced affinity towards carbon phases, potentially compromising the composite interfaces, and nickel and tungsten that are mild and strong carbide formers, respectively, displaying thus intermediate and strong carbon affinities. For the latter matrices, dispersing carbon phases represent a challenge due to carbide conversion.

The materials produced are designated as Cu-10nD, Ni-10nD and W-20nD (where 10 and 20 indicate the atomic fraction of nD). Close monitoring of the milling conditions enabled to homogeneously disperse the carbon phases and obtain nanostructured matrices (Figures 1 (a-c)), as well as to minimize milling media contamination and carbide formation, especially in the case of the W-based composite. Apparent interfacial bonding could be inferred the from transmission electron microscopy (TEM) images.

The metallic matrices have been subsequently dissolved to allow for a detailed analysis of nanodiamond. Electron diffraction demonstrated that its crystalline structure was preserved during milling (Figure 2). Microhardness measurements revealed remarkable strength enhancements of the nanostructured composites over that of pure metals of comparable grain sizes (Table 1). The strengthening mechanisms that justify the hardness increments in Cu-10nD and Ni-10nD include second-phase reinforcement (due to the potential load bearing ability of diamond), as well as Orowan and solid solution strengthening. The hardening effect observed in the W-20nD composite over that of pure milled tungsten is probably related to the nanodiamond reinforcement, nevertheless the influence of a fine dispersion of carbides cannot be ruled out.

This work has been performed under the Contract of Association between EURATOM and Instituto Superior Tecnico. Financial support was also received from the Fundação para a Ciência Tecnologia (FCT) grants with references PTDC/CTM/100163/2008, Pest-OE/SADG/LA0010/2011 and PEST-OE/CTM-UI0084/2011.

Tungsten (W) was select for an extensive use in nuclear fusion devices due to its low neutron activation, high melting point and sputtering threshold as well as low hydrogen inventory. Nevertheless, W is brittle at low and moderate temperatures, which results in abnormal thermal stress, component fracture and extra erosion under reactor operation due to inherent thermal cycling events. An attractive way to solve these problems involves the addition of other refractory metals in the W matrix and tantalum (Ta) is a natural candidate. It has a high ductility, toughness and radiation resistance relative to those of W and transmutes to W by high-energy neutron irradiation. Recently, IST proposed the production of W-Ta composite by mechanical synthesis.

The composite should reveal the individual properties of the pristine phases as long as the interdiffusion between the components is significantly avoided during the consolidation/sintering route of the final material. Sintering operations at temperatures higher than 1300ºC lead to significant improvements in the final densification and thermal conductivity of the composites, which is crucial for fusion applications. However, W and Ta interdiffusion can be relevant above 1300ºC, mainly due to diffusion of W into Ta, and the aim of the present work is to control the mechanism.

W-Taf composites presenting 10 and 20 at.% of Ta where produced by alloying W powders and Ta fibres with a planetary ball milling route (MA) and by consolidating the mixture with spark plasma sintering (SPS) in the 1300-1600ºC temperature range. The final densifications remain fairly constant in both composites after sintering at different temperatures (83 to 87%) and the elemental interdiffusion remained low at 1300ºC. Nevertheless, the diffusivity of W in Ta became significant at 1600ºC, leading to the formation of a solid solution zone with a stoichiometry close to W16Ta84. The mechanism was followed by scanning electron and energy-dispersive X-ray spectroscopies (SEM/EDS; Figures 1 and 2, Table 1). Fabrication routes yielding high densifications and low interdiffusion are currently under investigation.

The work has been supported by the Contract of Association between Euratom and IST and by the Fund. Ciência e a Tecnologia contracts PTDC/CTM/100163/2008, Pest-OE/SADG/LA0010/2011 and PEST-OE/CTM-UI0084/2011.

The high melting point, high sputtering threshold and low tritium inventory rendered W as a potentially suitable material in fusion devices. The major problem associated with presently available tungsten grades as structural materials is its brittleness at lower temperatures. This is further worsened by irradiation embrittlement. A strategy for ductility improvement is producing a composite, with the brittle W matrix being reinforced by short fibres of tantalum. As Ta is more ductile than W it can therefore divert or stop cracks propagating in the W matrix. In the present research Ta short fibres and powder were used as reinforcement component for W by alloying Ta short fibres or powder in a W powder matrix. The composites were subsequently irradiated with deuterium to assess the retention of this hydrogenic species in the materials.

The irradiated composites, with Ta contents of 10 or 20 at%, were produced from pure elemental powders (W-Ta powder composites), and pure W powder and Ta fibre (W-Ta fibre composites) with 100 μm in diameter by low energy ball milling in argon atmosphere. These materials were consolidated via spark plasma sintering (SPS) in the temperature 1200 to 1600 ºC range. Pure W and Ta plates (controls) and W-Ta composites were irradiated with He+ ions (optional pre-implantation step) and D+ ion beams at room temperature with fluences in the 1020-1021 at/m2 range. Blistering and deuterium retention in W and Ta plates and in W-Ta composites were studied with scanning electron microscopy (SEM), X-ray diffraction and thermal desorption analysis. The deuterium concentration was evaluated trough nuclear reaction analysis (NRA) using 0.75 to 2.1 MeV 3He+ beam and the D(3He,p)α reaction.

The investigations showed that deuterium irradiation induced microstructural modifications producing blistering in Ta plates as well as in W-Ta composites (Figure 1). These effects increased substantially in the Ta and W-Ta materials with the He pre-implantation step, while blisters have not been observed in the W plates either for D+ or He+ plus D+ implantation. Higher deuterium retention was observed by thermal desorption for the composites than for the W plates. Moreover the present study revealed that D+ trapping in the composites is dependent on the microstructure with higher retention observed for fibers than for powder.

This work has been performed under the Contract of Association between EURATOM and Instituto Superior Tecnico. Financial support was also received from the Fundação para a Ciência Tecnologia (FCT) grants with references PTDC/CTM/100163/2008, Pest-OE/SADG/LA0010/2011 and PEST-OE/CTM-UI0084/2011. The authors wish to acknowledge Jorge Rocha the implantation in W-Ta samples.

Due to its good thermal and electrical conductivity, improved plastic properties and excellent corrosion and oxidation resistance, copper is being widely used worldwide. Nevertheless, for some particular application, it is still desirable to improve copper strength, wear and fatigue resistance properties. These characteristics can be enhanced by suitable modification of materials microstructure by using solid state processing techniques, such as Friction Stir Processing (FSP). This technique makes use of non-consumable rotating tools to induce heat and severe plastic deformation in the materials to be processed. The complex thermo-mechanical phenomena developed inside the stirred volume, promotes strong microstructural modifications, which cautiously controlled, enables deeply transforming the microstructure of the materials being processed. In fact, FSP thermo-mechanisms leads to significant grain refinement, which drove the use of this technique towards producing ultrafine grained structural metallic materials from aluminium and other ductile metallic alloys. Due to the high macro and microstructural heterogeneity resulting from FSP methodologies, as well as the extremely refined structure resulting from it, the microstructural characterization of processed materials is an especially difficult task, which requires skilled researchers as well as important microscopy and microanalysis resources.

In present work, 1 mm thick plates of phosphorus deoxidised copper (Cu-DHP), temper class R 240, were friction stir processed using the conical and scrolled shoulder tools, shown in Figure 1, and varying processing parameters, namely, two different tool rotation rates (ω = 400 and 1000 rpm) and a constant traverse speed (v) of 250 mm/min. The specimens for analysis were removed transverse to the processing direction, and prepared for both optical and TEM analysis. The optical micrograph images were obtained from polished specimens, etched with FeCl3 and Hid reagents. Samples for TEM were polished mechanically from both sides down to a thickness of about 0.15 mm and then electropolished using a double jet thinner. A dilute solution of orthophosphoric acid (2:1) at room temperature under 10V tension was used. TEM analysis was carried out at 100 kV.

A strong influence of the processing conditions on the microstructural refinement was observed, being found that the tool geometry, which has a close relation with the plastic deformation and dynamic recrystallization kinetics, inside the stirred volume, is determinant in FSP results. In Figures 2.a and b are shown, respectively, optical and TEM images of the non-processed material, showing a coarse grain structure with mean grain size of 18 sm. Most of the grains display families of parallel slip lines, as shown in the TEM image of Figure 2.b. In the same way, microstructural analysis of the processed samples revealed the formation of more or less refined grain structures, according to the processing conditions in use. In Figures 3 and 4 are shown pictures of processed samples, obtained using the conical and scrolled shoulder tools under hot (ω = 1000 rpm) and cold (ω = 400 rpm) processing conditions. For the samples processed with the conical tool and hot processing conditions (Figure 3.a), the average grain size (8 m) was clearly coarser than that of the sample processed at 400 rpm (Figure 3.b), for which the average grain size registered was 1 m. For the samples processed with the scrolled tool (Figure 4) no important differences in grain size were obtained when changing the tool rotation rate. A significant decrease in grain size, up to 500 nm, was registered for these samples. By comparing the results it is possible to conclude that, under similar processing conditions, the scrolled tool induced higher grain refinement than the conical tool, which is related with the stronger plastic deformation achievable with this geometry.

Rare-earth intermetallic compounds with high Fe concentrations and adopting the ThMn12–type and Th2Zn17-type structures have attracted considerable attention in the field of permanent magnets. A large number of experimental studies has been done on these compounds, which are usually measured on alloys structurally characterized only by powder X-ray diffraction (XRD). However, the materials are often multiphasic and their quenched or annealed microstructures evidence homogenization ranges, second phases (resulting from segregation) and on-going phase transformations that may not be easily detectable by XRD. Additional microstructural studies on these systems are therefore required.

Among the Fe-based systems, the ThMn12–type and Th2Zn17–type structures usually require stabilization by a third element, such as Ti. In the present work Nd:11Fe:Ti has been prepared by melting Nd, Fe and Ti in an arc furnace followed by subsequent splat-quenching and/or annealing treatments. The resulting materials have been characterized by XRD, scanning and transmission electron microscopy coupled with energy dispersive spectroscopy.

The results have shown that the presence of α-Fe(Ti) could not be avoided during the solidification of the Nd:11Fe:Ti alloy. Furthermore, the microstructure morphologies and elemental analyses showed that at moderate cooling rates a secondary crystallization phase of Th2Zn17–type appeared in the Nd:11Fe:Ti alloy as result of a peritectic reaction. This lower temperature phase was however not detected in the splat-quenched material, where the high cooling rate route suppressed its crystallization. Nevertheless during a subsequent heat-treatment at 800 ºC the following decomposition took place: NdFe11Ti → Nd2(Fe,Ti)17 + α-Fe(Ti) + Fe2Ti. This reaction had already been proposed by Jang and Stadelmaier, who suggested that the NdFe11Ti compound is unstable at temperatures below 1000 °C. The current study shows that this transformation results in the fine lamellar intergrowth of the Th2Zn17-type phase in ThMn12-type grains, displaying random distribution of planar defects (Figure 1). The reciprocal space of the combined parent and intergrown phases has been mapped through a series of 3-D microdiffraction experiments (Figure 2). This allowed to establish that the preferred orientation relation between the two phases is (020)1:12//(003)2:17 and [100]1:12//[110]2:17, with the invariant plane sitting at 1:12//(333)2:17 planes.

The work was supported by the Portuguese Science Foundation through the CTM/48617/2002, PEst-OE/CTM-UI0084/2011 and CFMC-PEst-OE/FIS/UI0261/2011 grants.

Polymer nanocomposites are a recent class of materials that have drawn considerable attention in recent years, due to the significant improvements in several properties. Even though a lot of research has been performed on the preparation of these materials, the homogeneous dispersion of nanoparticles in polymeric matrices, especially in non-polar, is still a difficult task. Thus, frequently nanocomposites exhibited worst properties than conventional polymers that limit their effective application. One way to improve nanoparticles dispersion is by using an in situ sol-gel method, which is based on a reaction between a precursor, containing the inorganic particle, and a polymer followed by hydrolysis-condensation reaction. Therefore, the present work aims to use microscopy techniques to investigate the dispersion of nanoparticles containing aluminium in PP and EVA matrices, prepared by a sol-gel process in the melt.

Polypropylene modified with maleic anhydride (PP-g-MA, Polybond 3200) supplied by Crompton and ethylene-vinyl acetate (EVA) with 12 wt.% (EVA12, Escorene Ultra UL 00112) and 27 wt.% (EVA27, Escorene Ultra UL 00328) of vinyl acetate supplied by Exxon Mobil, were used as organic matrices to prepared the nanocomposites. The precursor, aluminium isopropoxide (Al(Pr-i-O)3), used as received in powder state, was supplied by Sigma Aldrich. Nanocomposites with the same composition were prepared by melt mixing in an internal mixer under constant processing conditions, as previously describe by Oliveira. The hybrid nanocomposite (HN) synthesized with PP-g-MA was called HN-Pr, with EVA12 was HNEVA12 and the one synthesized with EVA27 was HNEVA27.

Samples characterized by SEM were fractured at low temperature and gold coated. Samples analysed by TEM were sectioned by cryo-ultramicrotomy using a diamond knife at -60 ºC and -140 ºC under liquid nitrogen for EVAs and PP-g-MA nanocomposites, respectively. X-ray microanalysis mapping was performed in 300 μm2, in the same place where SEM analysis was made, with an energy dispersive X-ray Spectrometer (EDS) from Link eXL II from Oxford Instruments attached to the SEM.

SEM micrographs presented in Figure 1a, b and c show that while HN-Pr has a homogeneous and rough surface, HNEVA12 and HNEVA27 have homogeneous and smoother surfaces. The presence of nanoparticles agglomerations can not be observed in the micrographs, which indicates a good dispersion and interaction between organic and inorganic components. Therefore, in order to investigate nanoparticles dispersion TEM analysis were performed and the results presented in Figure 2 evidence different degrees of nanoparticles dispersion in polymeric matrices and distinct sizes. The best dispersion was achieved in HN-Pr followed by HNEVA27. The average particle size is 200, 130 and 120 nm for HN-Pr, HNEVA12 and HNEVA27, respectively. The differences in particles dimension can be explained by the extension of the chemical reaction, which in agreement with other techniques, it was higher for EVA27. EDS analysis results presented in Figure 3 render 2.84, 5.07 and 3.49 % of aluminium content in the analysed area of HN-Pr, HNEVA12 and HNEVA27, respectively.

In this study, it was observed that reaction extension has a great influence on size and dispersion of the generated nanoparticles. According to SEM and TEM results, the smallest nanoparticles were achieved in EVA27. Moreover, for the three nanocomposites prepared well dispersed nanoparticles were obtained. The EDS spectrum confirmed the presence of aluminium in nanocomposites structure.

This work showed that microscopic technics are very powerful on the characterization of new polymer matrix nanocomposites.

The authors are grateful to the Portuguese Foundation of Science and Technology (FCT) Project SFRH / BD / 39085 / 2007 for the financial support.

There is a wide range of surface analysis techniques which are, generally, complementary. Nuclear and non-nuclear techniques have been available. Nuclear techniques, which are non-destructive, provide for analysis over a few microns close to the surface of the sample, giving absolute values of concentrations of isotopes and elements. They have been applied in areas such as scientific, technologic, industry, arts and medicine, using MeV ion beams. Nuclear reactions permit tracing of isotopes with high sensitivities. We use ion-ion nuclear reactions, elastic scattering and the energy analysis method where, at a chosen energy of the incident ion beam, an energy spectrum is recorded of ions from nuclear events, coming from several depths in the target. Such spectra are computationally predicted, giving target composition and concentration profile information. A computer program has been developed in this context, mainly for flat targets. The non-flat target situation arises as an extension. Successful applications of the method are given using the 18O(p,α0)15N reaction and elastic scattering of (4He)+ ions. SEM and TEM are used as useful complementary techniques.

Two types of samples were prepared containing thick and thin oxides, respectively. The first sample (S1) was obtained by high temperature oxidation of austenitic steel in C 18O2 gas. Weight gain measurements had given a 4.2 μm thick oxide. SEM has shown a reasonably flat oxide (Figure 1 (a)). The second sample (S2, also labelled Al/Al2O3) was obtained by anodization of high purity aluminium at 100V in an aqueous solution of ammonium citrate. An oxide thickness of 0.1370 μm was expected. TEM has given an oxide film thickness of 0.1340 μm (Figure 1 (b)). The 18O(p,α0)15N reaction at Ep=1.78 MeV and 165º was used to analyse sample S1. Figure 2 (a) shows a good computed fit to data. A 18O step concentration profile was found, corresponding to a thick 18O oxide with thickness X1=4.4 μm. Sample S2 was analysed by elastic scattering of α particles at Eα=2.0 MeV and 165º. Figure 2 (b) shows a good computed fit to data. A thin oxide film thickness of X1=0.1350 μm was found, close to the TEM value. The fit also shows a ratio of atomic densities of O and Al slightly above 1.5. The combined use of nuclear techniques, SEM and TEM microscopy has proved to be very important for surface analysis of materials. The reported results would be difficult to obtain by other techniques.

Supports from University of Beira Interior and FCT (Fundação para a Ciência e a Tecnologia)/PEst-OE/FIS/UI0524/2011 (Projecto Estratégico-UI524-2011-2012) are acknowledged.

Rare-earth intermetallic compounds adopting the tetragonal ThMn12–type structure and containing high Fe concentrations have attracted considerable attention in the field of permanent magnets. Among them, the Y-Fe-Mo series has been extensively investigated, especially by X-ray diffraction (XRD), but the microstructural characterization was very limited.

In the present work, Y:11Fe:Mo has been prepared by melting Y, Fe and Mo in an arc furnace followed by splat-quenching and/or annealing treatments. The structure, chemistry and magnetic domain configurations of the resulting polycrystalline aggregates have been investigated by XRD, scanning and transmission electron microscopies (SEM and TEM, respectively), energy dispersive X-ray spectroscopy (EDS) and Lorentz microscopy.

A special emphasis was given to Lorentz microscopy, where contrast is based on the Lorentz deflection imposed on electrons by the passage through a magnetic specimen. The magnetic domains have been imaged by the intermediate lens in Fresnel mode, with the objective lens switched off. In these conditions the intermediate lens is defocused so that out-of-focus images of the specimen are formed: the magnetic domain walls are imaged as alternate bright (convergent) and dark (divergent) lines. For the overfocused image, bright lines occur at the position of domain walls for which the magnetisation on either side is deflecting the electrons towards the wall, whereas dark lines are observed at the walls for which the magnetisation on either side is deflecting the electrons away from the wall. The opposite contrast is observed at the underfocused image.

The results have shown that the tetragonal YFe11-xMoy phase is predominant, with a cellular dendritic morphology (Figure 1), but a considerable presence of -Fe(Mo) could be inferred, forming a coarse intercellular eutectic mixture. Significant Fe segregation occurred during annealing. However, this composition variation corresponded to an extremely limited evolution of the lattice parameters, the Rietveld analysis pointing to Fe vacancies at the 8i sites on the annealed material. XRD and EDS results indicate that the fraction of point defects in the ThMn12-type structure adapts to the processing route and that the stable configuration depends on the temperature. The current study also showed that grain boundaries are usually associated with domain walls and that YFe11Mo grains present internal domain walls forming stripe/maze patterns characteristic of high anisotropy materials (Figure 2), while residual -Fe(Mo) grains exhibit vortex configurations (see arrows in Figures 2 (a-c)).

The work was supported by the Portuguese Science Foundation through the CTM/48617/2002 and PEst-OE/CTM-UI0084/2011 grants.

ION JELLY® patented technology is based on the cross-linking of Ionic Liquids (ILs) with Gelatin that results in a viscous gel that can be molded into a film or a block, and solidifies by cooling below 35 ºC . The outcome of this combination is a transparent, light and flexible conductive polymer that adapts perfectly to a great variety of surfaces. Some of the key properties of ION JELLY® are: high stability up to 180ºC, large electrochemical window and bio-compatibility. Taking in consideration the attractive attributes of ILs, that provide a stable and friendly environment for the enzymes, where they retain their catalytic activity, combined with the morphologic advantage of gelatin, we have decided to study this new protein-ionic-based material regarding water content, swelling behaviour, and structural morphology by scanning electron microscopy (SEM).

The properties of [emim][EtSO4] and [bmim][N(CN)2] ION JELLY® films were compared with those of solely gelatin. Thin films were prepared with different amounts of water or phosphate buffer and left to maturate in a controlled atmosphere for 4 days. Swelling was carried out in water at 4ºC and films were lyophilized afterwards. SEM images of ION JELLY® and gelatin films were obtained prior and after these steps.

ION JELLY® films were rubbery while gelatin films were glassy. Water-made ION JELLY® had completely smooth surfaces, just like gelatin, but buffer-made ION JELLY® exhibited salt crystals on the surface, as well as some superficial pores (Figure 1). Free water content in [emim][EtSO4] ION JELLY® was found to be greater than [bmim][N(CN)2] ION JELLY® and gelatin.

The swelling ratio of both types of ION JELLY® was close to 100%, while gelatin swelled 8 times more. The swollen lyophilized gelatin films formed a heterogeneous and highly porous network (Figure 2), while ION JELLY® films were more homogeneous with a lower degree of porosity (Figure 3).

These results showed that ION JELLY® is a polymer with a more tightly bound structure than gelatin. This material allows water to penetrate, but possesses a higher rigidity that prevents too much mobility of the polymeric chains. Considering that it’s a biocompatible polymer, lyophilized swollen ION JELLY® could have potential applications as a scaffold for biological material.

Financial support received from the Portuguese Science and Technology foundation (Fundação para a Ciência e Tecnologia) under the grants SFRH/BD/77568/2011, PTDC/EBB-BIO/114288/2009, PTDC/EBB-BI/099237/2008 and SFRH/BPD/41175/2007 and Projecto Estratégico IBB: PEst – OE/EQB/LA0023/2011

A gold solidus of Valentinian I, Emperor of Rome (A.D. 364-375) shown in Figure 1, and belonging to a private collection, was subjected to material and stylistic analysis, in order to ascertain about its authenticity. Due to the rarity of such a coin, only non-destructive analytical techniques were used, namely Scanning Electron Microscopy (SEM), Particle Induced X-ray Emission (PIXE), electrical resistivity and optical microscopy.

Examination by SEM revealed that, in common with coins minted by this emperor, the solidus was die-struck as evidenced by the surface flow lines indicating metal movement under the dies (Figure 2). Wear traces presented an unorganized pattern. The coin was also examined for signs of stress-corrosion cracking but no evidence of this were found. The coin also shows traces of what appear to be soil residues; small quantities of these residues can also be seen in porosities in the coin face (arrow in Figure 3).

Analysis by PIXE showed that the coin was made from an alloy of gold (97.9%), silver (2.0%) and copper (0.1%) (Figure 4). The high gold content is likely to be overestimated due to surface depletion of the silver and particularly the copper, which is caused by slight dissolution of these more reactive metals in the burial environment. Nevertheless, this effect is usually small and in agreement with other solidus from Valentiniano I. Also, the high gold content may lie behind the lack of stress-corrosion cracking.

The presence of platinum group element (PGE) inclusions is, in some cases, indicative of alluvial gold provenience. Both, optical microscopy and PIXE, were used to detect them but it was not possible to identify their presence. Typically, the concentration of these elements is in the order of ppm, although for this specific period different values have been reported. Considering the experimental conditions used (2 MeV accelerated proton beam and a 50 μm Mylar foil in front of the X-ray detector) the limit of detection of the PIXE technique is close to the expected trace concentration. More energetic proton beam (>3MeV) or the use of specific filter for the X-ray signal in the low energy region, i.e. Zinc foil 75 μm thick, are the future experiments to be carried out in order to detect the presence of such characteristics PGE elements.

In order to understand the presumable surface gold enrichment, electrical conductivity measurements were used. The values obtained (1.50-1.56)x1017 S/m show a lower conductivity as compared with the reference value for a 97% Au, 3% Ag alloy (3.54x1017 S/m), indicating that indeed the coin bulk has a lower gold content.

As for the stylistic analysis, there is no sound agreement about the coin authenticity, but the tendency is to consider it a good one. The compositional and structural characterization of cultural heritage artefacts usually limit the number of available techniques to those considered as non-destructive and non-invasive, such the one presented in this work. This restriction also constricts and difficult the desired straight conclusions but, on the other hand, increase the multidisciplinary of the work, applying techniques usually dedicated to the material science characterization to cultural heritage.

V. Corregidor acknowledges the funding support from the FCT-Ciência program. Financial support was also received through the PEST-OE/CTM-UI0084/2011 and PEST-OE/FIS/UI0275/2011 grants.

The knowledge of our pre-history and ancient metal artefacts production methods can only be deeply investigated through the multidisciplinary approaches involving different analytical techniques including microscopy techniques. The present study concerns the elemental and microstructural characterization of pre-historic bronze artefacts from the Northwestern Iberia Peninsula. During Bronze Age an increment of metal artefacts production and its typological diversification is observed related to the development of metallurgical technology. Several artefacts have been found during recent excavations at the Bronze Age settlement of Fraga dos Corvos (Macedo de Cavaleiros, Portugal). The analysis of metallurgical remains points out to the existence of local metallurgical activities. Five bronze artefacts previously analysed by micro-EDXRF, an Acebuchal fibula fragment, two pendants and a riveted sheet (probably a fragment of a vessel or cauldron) with average concentration values of 10±1.1% Sn and ~2±0.5% Pb and a droplet (?) with ~5% Sn and ~4% Pb, were selected for optical microscopy (OM) and SEM-EDS analysis.

Microscopy observations showed to be very important for the comprehension of pre-historic bronze metallurgy, allowing the identification of different phases, inclusions and thermomechanical processes applied during artefacts production. The fibula and the pendants show an equiaxed and twinned microstructure with slip bands (Figure 1 (a) and (c)). The characteristics observed are related to recrystallized and plastically deformed α-Cu structures. These features indicate that the artefacts were hammered and annealed (thermomechanical cycling), ending with a hammering operation. The pendants only exhibit slip bands near the surface, probably resulting from a finishing operation. Lead and Cu-S inclusions are frequently observed. The riveted sheet has an annealed microstructure with large α-Cu grains, undissolved (α+δ) eutectoid and few annealing twins. Elongated Cu-S inclusions, lead globules and pores were identified by SEM-EDS (Figure 1 (a)). Its microstructure indicates that shaping was obtained by just one or few thermomechanical cycles. The droplet presents a coarse and cored dendritic structure (Figure 1 (b)). Rounded Cu-S inclusions, lead globules and pores were also observed. Those are characteristics of a slow cooled as-cast alloy. Due to its low Sn content the (α+δ) eutectoid is absent. As a final note, microscopy techniques allowed establishing the manufacture processes involved in bronze metallurgy and to conclude that different thermomechanical processes were applied according to the typology of the artefact.

Financial support received from the Portuguese Science and Technology foundation under the EarlyMetal project PTDC/HIS-ARQ/110442/2008 and the grants SFRH/BPD/73245/2010 (EF) and SFRH/BD/72369/2010 (EL). Financial support of CENIMAT/I3N through the Strategic Project LA25/2011-2012 (PEst-C/CTM/LA0025/2011) is gratefully acknowledged.

Laser ablation using ultrafast femtosecond lasers and holographic schemes has proven to be a powerful and versatile tool for surface and volume structuring. The principle of operation of this technique is simple: when two or more pulses overlap in time and space, an interference pattern is generated that can be used to create periodic surface structures. In addition, due to the extremely short pulse duration, a very high peak power is achieved leading to intense non-linear effects. As a result, almost any type of material can be processed without undesirable collateral thermal effects.

In this paper, characterization of two-dimensional (2D) patterns generated in titanium using femtosecond laser radiation has been carried out using scanning electron microscopy (SEM). The laser source is a commercial Yb:KYW laser system providing pulses with a duration of 560 fs at a central wavelength of >= 1030 nm. The surface topography was characterized using a Hitachi S2400 scanning electron microscope operated at an electron acceleration voltage of 25.0 kV. Laser processing was performed in air on polished grade 2 titanium samples, a material typically used in low load bearing medical devices.

One-dimensional (1D) gratings were created using a modified Michelson interferometer described in detail elsewhere (Oliveira et al., 2012). To create 2D gratings a double exposure method was used. First, 1D gratings were produced in linear tracks by translating the sample relatively to the stationary interfering laser beams with a fixed scanning velocity of 0.1 mm/s. As an example, Figure 1 depicts SEM pictures of horizontal and vertical 1D gratings with period of about 3.9 m, generated using a pulse energy and pulse repetition rate of 0.35 mJ and 100 Hz, respectively. The peak to valley distance of these patterns can be controlled either by changing the scanning velocity or the pulse repetition rate. By overlapping two linear tracks, different kinds of 2D structures can be created. Figure 2 depicts a square pattern obtained by overlapping two 1D gratings rotated by 90°. The dimensions of the squares depend on the one-dimensional gratings period, which in turn can be easily controlled by varying the distance between the interfering beams. Figure 3 depicts two other possibilities: i) trapezium-like patterns obtained by rotating the 1D gratings by 45°, and ii) rectangular patterns obtained using 1D gratings with different periods and rotated by 90°.

The proposed optical setup offers a simple method of texturing the surface of materials and, hence, to control surface properties such as wettability. In the case of titanium, this is particularly important because surface texturing enhances its osseointegration ability. For this purpose, when compared with the columns spontaneously formed on titanium surfaces treated with femtosecond laser radiation, these 2D gratings present the major advantage of being size and shape-controllable.

Cemented tungsten carbides (WC), are considered one of the oldest, most successful and commercialized powder metallurgy products. These materials are commonly composites of WC powder particles bonded with transition metals such as Co or Ni via liquid-phase sintering. WC-based composites have been used for decades in wide engineering applications, as cutting tools, components for oil and gas drilling, metal forming, among others. The conventional processing of the WC based composites initializes with powder preparation, performed by wet milling of all the powder components (WC and metallic binders). However, this process is high energy consuming, ecologically unfriendly and longstanding, thus new powder processing methods are welcome. In this work, copper (Cu) was selected as an alternative binder, due to its inability to form brittle carbides with WC at higher temperature, the superior ductility (compared with the traditional Co binder) and corrosion resistance. Nevertheless, melted Cu has low wettability on the WC surfaces, limiting the attained sintered density and, consequently, the final properties. Powder coating techniques, such as high energy ball milling (HEBM) and the sputter-coating technique (ST), improve the binder homogeneous distribution and nanostructuring enhancing the sinterability. WC-Cu composite powders (with 2 wt.% Cu) were prepared using the two methods mentioned above. The morphology of the particles was evaluated by scanning electron microscopy (SEM- Hitachi SU-70) and the distribution and chemical composition were assessed by energy dispersive spectroscopy (EDS- Bruker QUANTAX 400).

The starting WC powder has an average grain size of 9 µm, as depicted in Figures 1-a) and 2-a). In the WC coating by HEBM, the collisions of ball-to-ball and ball-to-wall with the entrapped powder particles cause at the same time severe binder plastic deformation and WC fragmentation, endorsing a high uniform distribution of Cu around WC particles, as is depicted in Figures 1-b) and c). On the other hand, the composite powders prepared by ST revealed a high uniformity of Cu coating on the WC particles (Figures 2-b) and c)), together with a columnar binder nanostructure, commonly observed on sputter–coated surfaces. In spite of the low binder content, the WC particles seem well covered, taking its rough morphology, in Figure 2-c), and the X- ray maps and the Cu, W concentration profiles presented in Figure 3. It can be, therefore, concluded that both powder coating techniques allow high uniform distribution of Cu coatings on WC particles and, furthermore, the ST technique presents a clear nanometric binder structure. The effect of the coating technique on the sinterability of WC-Cu powders will be evaluated on forthcoming studies.

Conservation of natural resources, shortage of waste land and the high cost associated to treatment prior to disposal are driving growing interest in the recycling of construction and demolition waste materials (CDW). A challenging application for recycled CDW is the replacement of natural aggregates in the production of structural concrete. In the past few years several studies have examined the viability of this substitution. Although recycled aggregates are mostly heterogeneous, less dense and more porous than natural aggregates, satisfactory results have been attained by several authors regarding concrete workability, mechanical properties and durability. However, a systematic microstructural characterization of recycled aggregate concrete is still unaccomplished.

In this context, the use of fine recycled concrete aggregates to replace natural fine aggregates in the production of structural concrete was tested, and attained microstructures are reported. The recycled aggregates were obtained from a standard concrete, produced and crushed under laboratorial conditions, thus allowing full control of concrete’s composition and setting. The used raw materials were natural aggregate (sand), recycled aggregates and Type 1 Portland cement. The substitution extent in the mixtures was 0, 10, 50 and 100 wt%; hydration was stopped at the ages of 9 h, 24 h, 96 h and 28 days. Microscopy study of the different mixtures enlightened the effect of the incorporation of recycled aggregates upon the formation and morphology of the different concrete hydration products. In this work, FEG-SEM (coupled with EDS microanalysis) was used on polished cross sections and fracture surfaces, to study the new mixtures. Focus was placed on the interfacial transition zone (ITZ) between cement matrix and aggregate.

The natural aggregate-cement interfacial zone exhibits typical microstructural features of the ITZ of a normal strength concrete. After 28 days a large amount of well-crystallised C-S-H (and a small amount of poorly crystalline fibres) is present at the interface, together with CH deposits. Grains of unreacted clinker components (C2S, C3S, Ca2(Al,Fe), C3A) were also identified; ettringite crystals are barely present, even at the earlier hydration times. The ITZ is highly porous. Independently of the setting time, fracture takes place preferably along the surface between paste and aggregate, attesting the relatively loose nature of the interface. The structure of ITZ with recycled aggregates (Figure 1) is consistent with that observed in the reference natural concrete. Also, calculation based on EDS results rendered a lime to silica ratio (C/S) of 1.46 0.15, consistent with the typical 1.2-2.3 range. However, there are representative microstructural features that may contribute to variation of mechanical properties. Ettringite and plate-like CH hydrates are much more abundant, even at higher setting times. Overall porosity in the ITZ increases with the aggregate substitution extent; however maximum pore size decreases from approximately 30 µm for 0% substitution to 16 µm for 100 % substitution, as shown by image analysis results. In fresh natural concrete a water film forms around the aggregates, which is gradually replaced by the growing amount of hydration products. In recycled aggregates, active silica in residual cementitious materials reacts with the fresh cement hydration products. The secondary reaction products gradually fill the region, partially covering the recycled aggregates pore structure and creating additional interfacial bonding effects (Figure 2). In good agreement, it was observed that in substituted concretes fracture preferably takes place throughout the paste rather than throughout the contact surface.

Concretes prepared with recycled aggregates exhibit typical microstructural features of the ITZ in normal strength concrete. Although porosity at the ITZ is affected by the extent of aggregate replacement, the interfacial bond is apparently stronger when recycled aggregates are used. This envisages an opportunity window for the development of increased strength Portland cement concretes.

The Castro de Vila Nova de São Pedro (VNSP) is an emblematic settlement located at Azambuja (Portugal), occupied predominantly during the Chalcolithic period. A large and diversified metallurgical collection was recovered from this settlement which includes artefacts, crucibles and other metallurgical production remains, like slags and droplets. The chemical and microstructural characterization of this metallic collection aims to contribute to a better comprehension of the early copper-based metallurgy on the Portuguese Estremadura, the degree of knowledge of the ancient metallurgists and the role of the metallurgical activities in Chalcolithic societies.

A group of 53 selected copper-based fragments of artefacts plus metallurgical production remains (12 crucibles and 20 slags and droplets), all belonging to VNSP, were characterized by using different analytical techniques: EDXRF and micro-EDXRF spectrometry, optical microscopy (OM) and SEM-EDS. The EDXRF and micro-EDXRF spectrometry gives the elemental composition of the artefacts and metallic nodules. The microscopy techniques play a fundamental role in the chemical and microstructural characterization of artefacts and metallurgical remains. The OM allows the identification of different phases, inclusions and thermomechanical processes applied during the shaping of the artefacts. The SEM-EDS plays an important role in the determination of main chemical phases present in the metal alloy and slags, and also in the distribution of chemical elements and minerals in the inclusions. The combination of these two microscopy techniques gives indication of the processes used in the reduction of minerals in order to obtain the metal and also allows the characterization of the operation chain, regarding the production of artefacts.

The research that has been carried out by us offer indications concerning the provenance of the arsenic, the technological choices involved in the production of an arsenical copper alloy and how it was recognized by ancient metallurgists. Results obtained on the elemental composition of the metallurgical production remains are consistent with copper and arsenical copper (As > 2 %) artefact production. Crucibles and slags analysed indicate melting and smelting operations (of copper ores or copper/arsenic ores). A statistically significant association was found between copper alloyed with arsenic and artefacts classified as tools/weapons (arrowheads, daggers and knives). In several cases, the presence of arsenic rich phases in the microstructure, resulting from an inverse segregation phenomenon, shows no evidence of chemical homogeneity control during the artefact manufacture. Microstructural analyses also show that the majority of the artefactual group was shaped with forging plus annealing operation cycles and 23 % of the artefacts received a final forging treatment. This final treatment was associated to artefacts presenting higher arsenic contents.

This research work has been financed by the Portuguese Science Foundation (FCT-MCTES) through the EarlyMetal project (PTDC/HIS-ARQ/110442/2008) and the PhD Grant SFRH/BD/78107/2011 (FP). The financial support of CENIMAT/I3N through the Strategic Project-LA25-2011-2012 (PEst-C/CTM/LA0025/2011) is also acknowledged.

Although eyedrops are nowadays the most used administration form of ophthalmic drugs, they present several problems: they imply repeated applications, lead to significant drug losses, and may cause undesirable side effects, as a result of the rapid drug absorption into the blood stream. Several attempts have been made to develop new drug delivery systems, which increase the residence time of the drugs in the eye and improve its bioavailability. Therapeutic soft contact lenses (SCLs) seem to constitute a promising alternative due to the prolonged contact with the eye. Although drug soaked contact lenses have demonstrated to be more efficient than eyedrops, they still present limitations: maximum drug load is limited and diffusion is the only resistance to drug transport across the gel, which may lead to short release times. Designing an effective system for the treatment of ocular diseases is a challenging task, to which nanotechnologies may give a valuable contribution. The incorporation of drug-loaded nanostructures in the SCLs materials may help to control the drug release rates and to maintain drug therapeutic levels for longer periods of time.

The main objective of this work is to produce hypromellose phthalate (HPP 50) nanoparticles (NPs) containing levofloxacin (LOF) to incorporate in hydrogels for SCLs. LOF is an antibiotic which offers a broad spectrum against ocular infections and is used both in prophylaxis and treatment. The NPs were produced using a supercritical atomization process developed by the research team - Supercritical Enhanced Atomization (SEA) and were engineered in order to improve the release rate of LOF. Different working pressures, LOF concentrations and polymer+antibiotic starting solution concentrations were tested. The morphology and size of the obtained particles were analysed by scanning electron microscopy (SEM) (Figure 1). The release profiles of the drug were determined using a standard dissolution tester. The quantification of the drug in the supernatant was done by high performance liquid chromatography (HPLC). The particles which presented the best release rate were SEA 15 (Figure 2), containing 10% w/w of LOF and produced at 20 MPa with a concentration of polymer+antibiotic of 5 mg/mL. These particles were further characterized by dynamic light scattering (DLS) (Figure 3), which confirmed the wide size dispersion of the particles, and by zeta potential measurements, which gave a slightly negative potential, -10 mV.

Future work may involve both the optimization of the experimental conditions to decrease the size dispersion of the particles and their eventual coating with polyelectrolytes in order to extend the drug release time.

This study was financially supported by the project PEst- OE/QUI/UI0100/2011. Patrizia Paradiso acknowledges grant from the project SFRH/BD/71990/2010.

Welding is the principal industrial process used for joining metals. However, it can produce dangerous fumes that may be hazardous to the welder’s health and it is estimated that, presently, 1-2% of workers from different professional backgrounds (which accounts for more than 3 million persons) are subjected to welding fume and gas action. With the advent of new types of welding procedures and consumables, the number of welders exposed to welding fumes is growing constantly in spite of the mechanization and automation of the processes. Simultaneously, the number of publications on epidemiologic studies and the devices for welders’ protection is also increasing. Apart from that, the influence of very ultrafine particulate, lying in the nanoparticles range, on human health has been pointed to be of much concern as airborne nanoparticles are resulting both from nanotechnologies processes and also from macroscopic common industrial processes such as welding. In fact, nanotoxicological research is still in its infancy and the issuing and implementation of standards for appropriate safety control systems can still take several years. Yet, the advanced understanding of toxicological phenomena on the nanometre scale is largely dependent on technological innovations and scientific results stemming from enhanced R&D. Meanwhile, the industry has to adopt proactive risk management strategies in order to provide a safe working environment for their staff, clients and customers, and obtain products without posing health threats at any point of their lifecycle. Understanding the relationship of airborne nano sized particulate and human health, under different environmental conditions is of great importance for improving exposure estimates and for developing efficient control strategies to reduce human exposure and health risk and for establishing, evaluating and improving regulations and legislation both on air quality, airborne emissions and the incorporation of nano sized materials in other products and commodities.

Mass measurement methods are not sufficiently sensitive for airborne nanoparticles and are not sensitive toward the specific health relevant properties of nanoparticles. The most sensitive concentration measured in this particle range (> 100 nm diameter) is the number concentration. In fact, surface area is a relevant metric for nanoparticles, as most of the processes in the human body environment take place via the particle surface, which is increasing significantly with decreasing particle size in the nanometer size range for the same amount of mass. In order to perform the toxicological assessment of welding processes a Nanoparticle Surface Area Monitor, TSI, Model 3550, based on diffusion charging (measuring the electrostatic charge on a sampled aerosol, mainly composed of nanoparticles) was used for monitoring the emission of nanoparticles resulting from several welding processes. This equipment indicates the human lung-deposited surface area of particles expressed as square micrometers per cubic centimeter of air (µm2/cm3). Although this instrument is very precise and its use has been validated for this purpose, the definite presence of nanoparticles in welding fume has to be complemented by microscopy techniques such as transmission electron microscopy (TEM), which has proved very helpful in order to establish the size, shape and aggregation habit of sampled aerosols, as well as energy dispersive X-ray spectroscopy (EDS) for performing the chemical analysis of collected nanoparticles. Figure 1 shows the aspect of aggregates of particles, in the nano size range, collected from welding fume during shielded metal arc welding (SMAW) of carbon steel and friction stir welding (FSW) of aluminium alloys, respectively. As expected in arc welding aggregates of larger dimensions are produced in more roundish shaped particles while in FSW these are finer. Chemical analysis determined by EDS showed that the emitted nanoparticles of SMAW are mostly resulting from burning of electrode coating and less from its core. Therefore, in order to reduce particulate emissions, special care has to be paid to the chemical composition of the electrodes coating.

The work was supported by the Portuguese Science Foundation through PEst-OE/EQB/LA0023/2011, PEst-OE/EME/UI0667/2011 and PEst-OE/CTM-UI0084/2011 and grants.