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The pantograph–catenary dynamic interaction analysis program (PantoCat) addresses the need for a dynamic analysis code able to analyse models of the complete overhead energy collecting systems that include all mechanical details of the pantographs and the complete topology and structural details of the catenary. PantoCat is a code based on the finite element method, for the catenary, and multibody dynamics methods, for the pantograph, integrated via a co-simulation procedure. A contact model based on a penalty formulation is selected to represent the pantograph–catenary interaction. PantoCat enables models of catenaries with multiple sections, including their overlap, the operation of multiple pantographs and the use of any complex loading of the catenary or pantograph mechanical elements including aerodynamic effects. The models of the pantograph and catenary are fully spatial being simulated in tangential or curved tracks, with or without irregularities and perturbations. User-friendly interfaces facili...

Materials with a cellular structure are common in nature and an example of natural solid foam is trabecular bone. As for other materials, the microstructural features of cellular solids affect their mechanical response. The aim of this work is to study how the trabecular bone microarchitecture affects the mechanical properties of two types of bone and compare the results with models existing on the literature for solid cellular materials. In spite of several works which make a more medical analysis, this type of materials-science approach is rare. Two types of trabecular bone were studied, namely from male and female patients with osteoporotic (fragility) fractures and patients with coxarthrosis, that were submitted to total hip arthroplasty. Each sample was first analyzed with micro-computed tomography, micro‑CT, for structural assessment. Several parameters used to characterize the three-dimensional structure of trabecular bone were obtained, including the bone volume fraction. Cylinder samples were also tested under uniaxial compression and the Young’s modulus and the ultimate stress were determined. No statistical differences between the two bone groups in respect to the structural and mechanical properties were found. The structural parameters that correlate better with the mechanical properties are different for each bone assembly, being the trabecular separation on the coxarthrosis group and the trabecular number on the osteoporotic group. However, both trabecular separation and trabecular number are strongly correlated with the bone volume fraction, i.e., to the bone relative density. The existing models of Gibson and Ashby were adapted to the relationship between stiffness and strength with the bone volume fraction. In both bone groups, the Young’s modulus is reduced with the decrease of the bone volume fraction following a quadratic law as happens in bending dominated open-cell foams. The ultimate strength is related to the bone volume fraction by a relationship with an exponent between 1 and 2, which indicates that during cell collapse, there is a mixture of two mechanisms: elastic buckling and brittle crushing.

Egg shells, shellfish shells and cuttlefish bones, high calcium content alimentary wastes, were used to prepare CaO sorbents for CO 2 capture. The materials were prepared by a simple procedure including two steps: crushing and calcination at 900 °C. Fine powders displaying chalky-white to pale grey-green shades were obtained depending on the starting material. All the prepared sorbents were microcrystalline limes containing various trace elements. The CO 2 sorption ability of the obtained lime materials was assessed using cycle carbonation/calcination tests by thermogravimetry. The CO 2 sorption profiles showed two regions: an initial region controlled by chemical reaction and a second region with diffusional control. The rate of chemical reaction of carbonation was almost invariant with the nature of the biomaterial used to produces the sorbent. The decarbonation (calcination step) was much faster than the carbonation for all the examined sorbents and also almost invariant with the sample. The diffusion rate depends on the calcite film thickness formed during chemical reaction controlled region. Results showed that alimentary wastes with high calcium content can be used to produces CO 2 sorbents thus contributing to mitigate the anthropogenic carbon and the environment contamination with alimentary wastes.

The research results presented in this paper are part of a larger study on the materials and techniques used in polychrome altarpieces of gilded woodcarving decoration ("talha dourada") in Portugal. The paper focuses on a narrative Portuguese Altarpiece from Mir- anda do Douro, considered one of the masterpieces of "talha dourada" among all the retables of the Iberian Peninsula in XVII th and XVIII th centuries. Although on the Portuguese territory, the altarpiece was made by artists from the Royal Spanish school of Valladolid, under a mannerist style. Thus the study opens a window on the artists' circulation between Spain and Portugal and influences of the Spanish schools in Baroque epoch on the Portuguese "talha". During its history this altarpiece underwent several transformations and extensive conservation treatments in 1989. On this occasion more than 50 samples were collected and analyzed using an interdiscipli- nary multi-technique methodology. 27 of these samples are chosen for this study in order to investigate the chromatic palette, the materials and techniques used in the polychromy of the retable. A novel protocol of investigation using different conventional and unconventional ana- lytical techniques (OM 1 fluorescent staining tests on cross-sections, Raman microscopy, XRD, XRF, X-ray micro-CT, SEM-EDX, MALDI-TOF-MS and LC-MS/MS) was established within an innovative research project (http://sites.fct.unl.pt/gilt-teller/) and applied on these samples. This protocol is necessary to confirm the results obtained in the 1989 campaign and to have further insight into the gilding and polychrome decoration materials and techniques and the additional information reported in the historical documents. The material and technical history of this im- portant altarpiece will be thus re-documented from a scientific perspective, meant to confirm and bring new information on the decorative technique used in the creation of this complex Por- tuguese monument. Microsc. Res. Tech. 76:733-743, 2013. V C 2013 Wiley Periodicals, Inc.

The aim of this study was to identify three-dimensional microstructural changes of trabecular bone with age and gender, using micro-computed tomography. Human trabecular bone from two disease groups, osteoporosis and osteoarthritis was analyzed. A prior analysis of the effects of some procedure variables on the micro-CT results was performed. Preliminary micro-CT scans were performed with three voxel resolutions and two acquisition conditions. On the reconstruction step, the image segmentation was performed with three different threshold values. Samples were collected from patients, with coxarthrosis (osteoarthritis) or fragility fracture (osteoporosis). The specimens of the coxarthrosis group include twenty females and fifteen males, while the fragility fracture group was composed by twenty three females and seven males. The mean age of the population was 69 ± 11 (females) and 67 ± 10 years (males), in the coxarthrosis group, while in the fragility fracture group was 81 ± 6 (females) and 78 ± 6 (males) years. The 30 μm voxel size provided lower percentage difference for the microarchitecture parameters. Acquisition conditions with 160 μA and 60 kV permit the evaluation of all the volume’s sample, with low average values of the coefficients of variation of the microstructural parameters. No statistically significant differences were found between the two diseases groups, neither between genders. However, with aging, there is a decrease of bone volume fraction, trabecular number and fractal dimension, and an increase of structural model index and trabecular separation, for both disease groups and genders. The parameters bone specific surface, trabecular thickness and degree of anisotropy have different behaviors with age, depending on the type of disease. While in coxarthrosis patients, trabecular thickness increases with age, in the fragility fracture group, there is a decrease of trabecular thickness with increasing age. Our findings indicate that disease, age and gender do not provide significant differences in trabecular microstructure. With aging, some parameters exhibit different trends which are possibly related to different mechanisms for different diseases.

The objective of this paper is to characterize self-compacting concretes produced with lightweight aggregates (SCLC) available in the Iberian Peninsula. The influence of different compositions on the self-compactability of SCLC is analyzed and some limits are suggested for their formulation. The usual self-compacting tests and additional segregation tests were considered. SCLC of adequate stability and self-compactability could be produced for compressive strengths between 37.4 and 60.8 MPa, density classes D1.8–D2.0 and 490–599 kg/m 3 of fines content with 33% fly ash by weight. Promising results were obtained in the SCLC mechanical characterization.

This article presents a detailed study of the microstructure of Iberian expanded clay lightweight aggregates (LWA). Other than more commonly used mercury porosimetry (MP) and water absorption methods, the experimental study involves optical microscopy, scanning electron microscopy (SEM), and microtomography (μ-CT). Pore connectivity and how it is deployed are shown to some degree, and the pore size spectrum is estimated. LWA are in general characterized by a dense outer shell up to 200 μm thick, encasing an inner cellular structure of 10–100 times bigger pore size. Aggregate pore sizes may span from some hundreds of nanometers up to over 1 mm, though the range of 1–25 μm is more typical. A noteworthy fraction of these pores is closed, and they are mainly up to 1 μm. It is also shown that macropore spatial arrangement is affected by the manufacturing process. A step forward is given to understanding how the outer shell and the inner pore network influence the mechanical and physical LWA properties, particularly the density and water absorption. The joint consideration of μ-CT and SEM seems to be the most appropriate methodology to study LWA microstructure. MP analysis is likely to distort LWA pore spectrum assessment.

When compared with road traffic, railway transportation is safer, more comfortable, less polluting and presents less energy consumption per passenger/km. When compared with the airplane, high speed trains are able to compete for short and medium distances, with the advantage of having better energy efficiency and causing less pollution. However, to maintain the operational performance of railway vehicles, it is necessary that the quality of the wheel–rail contact is controlled, which requires, among others, a good understanding of the wear mechanisms of the wheels and the consequences of their changing profile on vehicle dynamics. In this work, a computational tool that is able to predict the evolution of the wheel profiles for a given railway system, as a function of the distance run, is presented. The strategy adopted consists of a commercial multibody software to study the railway dynamic problem and a purpose-built code for managing its pre and post-processing data in order to compute the wear. Three alternative wear functions are implemented to compute the amount of worn material on the railway wheels. The computational tool is applied here to a realistic operational scenario in order to demonstrate its capabilities on wear prediction. Special attention is given to the comparison of the results obtained with the different wear functions implemented in this work and to the global and local contact models used in such formulations.

The wear evolution of railway wheels is a very important issue in railway engineering. In the past, the reprofiling intervals of railway vehicle steel wheels have been scheduled according to designers’ experience. Today, more reliable and accurate tools in predicting wheel wear evolution and wheelset lifetime can be used in order to achieve economical and safety benefits. In this work, a computational tool that is able to predict the evolution of the wheel profiles for a given railway system, as a function of the distance run, is presented. The strategy adopted consists of using a commercial multibody software to study the railway dynamic problem and a purpose-built code for managing its pre- and post-processing data in order to compute the wear. The tool is applied here to realistic operation scenarios in order to assess the effect of some service conditions on the wheel wear progression.

In order to develop more durable wheel materials to cope with the new specifications being imposed on wheel wear, a greater understanding of the wear mechanisms and transitions occurring in wheel steels is needed, particularly at higher load and slip conditions. The aim of this work was to draw together current understanding of the wear mechanisms, regimes, and transitions (particularly with R8T wheel material) and new tests on R7T wheel material; to identify gaps in the knowledge; and to develop new tools for assessing wear of wheel materials, such as wear maps, that can be used to improve wear prediction. Wear assessment of wheel materials, as well as wear rates, regimes, and transitions, is discussed. Twin disc wear testing, used extensively for studying wear of wheel and rail materials, has indicated that three wear regimes exist for wheel materials: mild, severe, and catastrophic. These have been classified in terms of wear rate and features. Wear rates are seen to increase steadily initially and then level off, before increasing rapidly as the severity of the contact conditions is increased. Analysis of the contact conditions in terms of friction and slip has indicated that the levelling off of the wear rate observed at the first wear transition is caused by the change from partial slip to full slip conditions at the disc interface. Temperature calculations for the contact showed that the large increase in wear rates seen at the second wear transition may result from a thermally induced reduction in yield strength and other material properties. Comparisons made between discs and actual wheels have provided some support for the theories relating to the transitions observed. Wear maps have been produced using the test results to study how individual contact parameters such as load and sliding speed influence wear rates and transitions. The maps are also correlated to expected wheel—rail contact conditions. This improved understanding of wheel wear mechanisms and transitions will help in the aim of eventually attaining a wear modelling methodology reliant on material properties rather than on wear constants derived from testing.

In this paper, an initial X-ray Computed Tomography study of sulphate salt degradation of two Portuguese Dimension Stones (“Semi-rijo” and “Mocacreme”) is presented, based on the Standard EN 12370 (1999). This study was performed using a high resolution X-ray Computed Tomography, a 3D X-ray microscopy non-destructive technique, in order to get representative digital information on 3D texture of the external surface and of the interior of visible light opaque objects for imaging and eventually measuring them, at resolutions in the m range. This will produce spatial quantitative information map on the density distribution of the scanned samples, usually associated to different mineral phases and voids’ textures constituting the natural materials. Both types of stones are also being investigated by the combined application of classic methods: Optical Microscopy, Scanning Electron Microscopy and Mercury Injection Porosimetry (MICP). Most of those classic studies use mainly traditional 2D imaging techniques, none of these being able to produce the 3D resolution details that X-ray micro-tomography enables. In order to achieve future better qualitative and quantitative integrated models, it will be important to combine its non destructive and 3D characteristics results with those of 3D MICP models obtained for such complex materials. This enables to qualitatively and/or quantitatively assess the evolution and decay potential of different phases and voids (pores + fissures) textures in different environmental interaction conditions. So, in order to set-up more efficient forecasts of their engineering properties behaviour in a given environment this study is an essential initial complementary step to compare and integrate in near future studies all the advantages and disadvantages of the application of these classic and new methods, based respectively upon visual examination of the samples’ exteriors and on micro-tomographic image models of the samples’ interiors and surfaces, to these geologic materials.

9 páginas.-- 3 figuras.-- 2 tablas.-- 83 referencias.-- Selected paper from the XVI Latin-American Congress on Chromatography (XVICOLACRO) and the 9th National Meeting on Chromatography (9ENC), 5–9 January 2016, Lisbon, Portugal., This study comprises an innovative approach based on the combination of chromatography (analytical pyrolysis and pyrolysis compound-specific isotope analysis (Py-CSIA)), light stable isotopes, microscopy and mineralogy analyses to characterize the internal layering of coralloid speleothems from the Ana Heva lava tube in Easter Island (Chile). This multidisciplinary proxy showed that the speleothems consist of banded siliceous materials of low crystallinity with different mineralogical compositions and a significant contribution of organic carbon. Opal-A constitutes the outermost grey layer of the coralloids, whereas calcite and amorphous Mg hydrate silicate are the major components of the inner whitish and honey-brown layers, respectively. The differences found in the mineralogical, elemental, molecular and isotopic composition of these distinct coloured layers are related to environmental changes during speleothem development. Stable isotopes and analytical pyrolysis suggested alterations in the water regime, pointing to wetter conditions during the formation of the Ca-rich layer and a possible increase in the amount of water dripping into the cave. The trend observed for δN values suggested an increase in the average temperature over time, which is consistent with the so-called climate warming during the Holocene. The pyrolysis compound-specific isotope analysis of each speleothem layer showed a similar trend with the bulk δC values pointing to the appropriateness of direct Py-CSIA in paleoenvironmental studies. The δC values for n-alkanes reinforced the occurrence of a drastic environmental change, indicating that the outermost Opal layer was developed under drier and more arid environmental conditions., A.Z. Miller acknowledges the support from the Marie Curie Intra-European Fellowship of the European Commission’s 7th Framework Programme (PIEF-GA-2012-328689). The Spanish Ministry of Economy and Competitiveness (MINECO, project CGL2013-41674-P) and the FEDER Funds are acknowledged for the financial support. N.T. Jiménez-Morillo thanks the MINECO for funding his pre-doctoral FPI fellowship (BES-2013-062573).

An excavation in a 14th c. church at Torres Novas, named Santa Maria do Castelo, provided some green glazed ceramic sherds, archaeologically dated from 14th c. to the 16th c. The town of Torres Novas is located at the center of Portugal, about 100 km north of Lisbon. The obtained results evidence three types of pastes of the pottery: type 1 with Quartz, Illite, Muscovite and Microcline as the main constituents, type 2 with Quartz, Calcite and Gehlenite; and finally type 3 with Quartz, Calcite and Diopside being the major components. Type 1 pastes are related to clay sources of Pliocene origin, and all this pottery was most probably made in Portuguese kilns. However, types 2 and 3 spectroscopic trends are remarkably different, indicating that those ceramics were produced in Seville. All the studied ceramics are lead glazed, and green glazed. In one of the samples from the Seville kiln, Cerusite was the main pigment used to obtain the greenish colouration. In what regards the origin of all samples produced with Pliocene clays, the 16th c. ones were most likely produced in the Santo Antonio da Charneca or Mata da Machada kilns, both located in the south shore of the Tagus river, region of Lisbon. In what regards the green glazed jug rim (14th c.) and the jug spout (15th c.) they could also have been produced in the two mentioned kilns south of Lisbon city, but another interesting hypothesis - due to richness of the decoration - is the production in Lisbon workshops, with the use of Pliocene clays imported by Lisbon potters, now documented both in Lisbon archaeological findings and also in documental sources.

Different in situ and laboratory tests are commonly used to determine the nature of salts and to improve the comprehension of degradation mechanisms. Although laboratory tests are more accurate, in situ tests yield faster results and require a significantly lower budget. This study aimed at collecting data on nine case studies of buildings (26 sample’s analysis) showing salt induced damage and assessing the potential of diagnosis techniques. Two in situ (test strips and a spectrophotometer-field kit) and three laboratory techniques [X-ray diffraction (XRD), X-ray fluorescence (XRF) and infrared spectroscopy (FTIR)] were carried out. The results showed the importance of collecting samples from different materials and locations. It is concluded that the combination of a thorough description of the areas affected by salt damage, a survey of the building’s history, the consideration of its surrounding environmental conditions, and simple in situ tests is a useful and straightforward diagnostic tool. A...

2 páginas.-- 2 figuras, Coralloid-type speleothems were found in Ana Heva lava tube from Easter Island (Chile). The ceiling of the lava tube presents light to dark brown speleothems with globular coral-like shape. To appraise their internal structure and composition, optical microscopy (OM) of cross-sections, field emission scanning electron microscopy with energy dispersive X-ray spectroscopy (FESEM-EDS) and X-Ray micro-computed tomography ( CT) were performed. The latter is a non-destructive method (NDM), performed to assess physical and compositional heterogeneities of the coralloids. The internal structure of these speleothems comprises a succession of thin layers, ranging from white to brown, with vitreous to resinous luster (Fig. 1A). According to their color and texture, four major layers are easily distinguishable, from the surface to their inner part: a superficial dark brown to black coating, with approximately 0.1 mm thick (L1); a 0.1-1 mm thick semi-transparent grayish layer (L2); a 0.1-1 mm thick white layer (L3), and a heterogeneous honey brown layer, with 1-5 mm thick and shades ranging from yellowish to honey brown (L4). FESEM-EDS microanalyses performed on the internal layers of longitudinally cut coralloid samples (Fig. 1B) showed systematic differences in chemical composition of the different color inner layers. In general, they contain variable proportions of Si, Mg and Ca (Fig. 1C-G). According to a previous study [1], the thin dark brown to black coating of the coralloid surfaces is probably derived from the weathering of the overlying volcanic rock and microbial activity [1]. The semi-transparent grayish layer (L2) is composed of low crystalline silica (opal-A), whereas the whitish layers (L3) are calcium carbonate (calcite). In contrast, the honey-brown layers (L4) present an unusual composition characterized by high levels of Mg, corresponding to an amorphous Mg hydrate silicate. Significant content of organic carbon was also found in these layers [1]. The CT study allowed us to confirm the existence of internal zoning in the studied coralloids (Fig. 2), and between them and the basaltic substrate. The brighter domains in the reconstructed images (Fig. 2D,E) correspond to the vacuolar basaltic. The other opaque domains, comprising thin spheroidal precipitates or dispersed spots within the coralloids (Fig. 2F-I), are calcium rich phases. According to mineralogical data and FESEM-EDS analysis, the inner/older spots correspond to apatite and the outer/more recent spots correspond to calcite. In contrast, the Si, Mg and C enriched domains are more transparent to X-ray radiation, combining at least two main phases (siliceous and magnesium silicate compounds). The proposed methodology was considered adequate for studying coralloid samples, by combining a NDM (μCT) with other microanalytical techniques. Investigations of speleothems using the potentialities of μCT provide general morphological and compositional information, suggesting the best approach for selecting and sectioning the samples. The FESEM-EDS provides characteristic information on the morphological, mineral and chemical composition., The authors acknowledge FCT for PEst-OE/CTE/UI0098/2011, AZM (SFRH/BPD/63836/2009) grant, and Spanish Ministry of Science and Innovation (Project CGL2011-2569) and CSIC 210230E125.

This paper assesses the physical, chemical and mineralogical characteristics of fine recycled aggregates obtained from crushed concrete waste, comparing them with two types of natural fine aggregates from different origins. A commercial concrete was jaw crushed, and the effect of different aperture sizes on the particle size distribution of the resulting aggregates was evaluated. The density and water absorption of the recycled aggregates was determined and a model for predicting water absorption over time is proposed. Both natural and recycled aggregates were characterized regarding bulk density and fines content. Recycled aggregates were additionally characterized by XRD, SEM/EDS and DTA/TG of individual size fractions. The results show that natural and recycled fine aggregates have very different characteristics. This should be considered in potential applications, both in terms of the limits for replacing amounts and of the rules and design criteria of the manufactured products.

Cellulose acetate (CA)–silver (Ag) nanocomposite asymmetric membranes were prepared via the wet-phase inversion method by dispersing polyvinylpirrolydone-protected Ag nanoparticles in the membrane casting solutions of different compositions. Silver nanoparticles were synthesized ex situ and added to the casting solution as a concentrated aqueous colloidal dispersion. The effects of the dispersion addition on the structure and on the selective permeation properties of the membranes were studied by comparing the nanocomposites with the silver-free materials. The casting solution composition played an important role in the adequate dispersion of the silver nanoparticles in the membrane. Incorporation of nanoscale silver and the final silver content resulted in structural changes leading to an increase in the hydraulic permeability and molecular weight cut-off of the nanocomposite membranes. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41796.

The development of polymer-calcium phosphate composite scaffolds with tailored architectures and properties has great potential for bone regeneration. Herein, we aimed to improve the functional performance of brittle ceramic scaffolds by developing a promising biopolymer-ceramic network. For this purpose, two strategies, namely, direct printing of a powder composition consisting of a 60:40 mixture of α/β-tricalcium phosphate (TCP) powder and alginate powder or vacuum infiltration of printed TCP scaffolds with an alginate solution, were tracked. Results of structural characterization revealed that the scaffolds printed with 2.5 wt% alginate-modified TCP powders presented a uniformly distributed and interfusing alginate TCP network. Mechanical results indicated a significant increase in strength, energy to failure and reliability of powder-modified scaffolds with an alginate content in the educts of 2.5 wt% when compared to pure TCP, as well as to TCP scaffolds containing 5 wt% or 7.5 wt% in the educts, in both dry and wet states. Culture of human osteoblast cells on these scaffolds also demonstrated a great improvement of cell proliferation and cell viability. While in the case of powder-mixed alginate TCP scaffolds, isolated alginate gels were formed between the calcium phosphate crystals, the vacuum-infiltration strategy resulted in the covering of the surface and internal pores of the TCP scaffold with a thin alginate film. Furthermore, the prediction of the scaffolds' critical fracture conditions under more complex stress states by the applied Mohr fracture criterion confirmed the potential of the powder-modified scaffolds with 2.5 wt% alginate in the educts as structural biomaterial for bone tissue engineering.

Sherds representative of the three Portuguese faience production centers of the 17th century – Lisbon, Coimbra and Vila Nova were studied with the use of mostly non-invasive spectroscopies, namely: ground state diffuse reflectance absorption (GSDR), micro-Raman, Fourier-transform infrared (FT-IR) and proton induced X-ray (PIXE) or X-ray fluorescence emission (XRF). X-ray diffraction (XRD) experiments were also performed. The obtained results evidence a clear similarity in the pastes of the pottery produced Vila Nova and some of the ceramic pastes from Lisbon, in accordance with documental sources that described the use of Lisbon clays by Vila Nova potters, at least since mid 17th century. Quartz and Gehlenite are the main components of the Lisbon’s pastes, but differences between the ceramic pastes were detected pointing out to the use of several clay sources. The spectroscopic trend exhibited Coimbra’s pottery is remarkably different, Quartz and Diopside being the major components of these pastes, enabling one to well define a pattern for these ceramic bodies. The blue pigment from the Lisbon samples is a cobalt oxide that exists in the silicate glassy matrix, which enables the formation of detectable cobalt silicate microcrystals in most productions of the second half of the 17th century. No micro-Raman cobalt blue signature could be detected in the Vila Nova and Coimbra blue glazes. This is in accordance with the lower kiln temperatures in these two production centers and with Co 2+ ions dispersed in the silicate matrix. In all cases the white glaze is obtained with the use of tin oxide. Hausmannite was detected as the manganese oxide mineral used to produce the purple glaze (wine color “vinoso”) in Lisbon.

The isothermal section of the ternary Eu-Ag-Ga system is studied at 500 °C for the 0-33.3 at.% Eu concentration region.

11 páginas.-- 8 figuras.-- 1 tabla.-- 33 referencias, Coralloid-type speleothems were recorded on the ceiling of the Ana Heva lava tube in Easter Island (Chile). These speleothems were morphologically, geochemically and mineralogically characterized using a wide variety of microscopy and analytical techniques. They consist dominantly of amorphous Mg silicate and opal-A. Field emission scanning electron microscopy revealed a variety of filamentous and bacillary bacteria on the surface of the Ana Heva coralloid speleothems, including silicified filamentous microorganisms. Among them, intriguing reticulated filaments resemble those filaments documented earlier in limestone caves and lava tubes. The identification of silicified microorganisms on the coralloid speleothems from the Ana Heva lava tube suggests a possible role of these microorganisms in silica deposition. © 2014 Copyright Taylor and Francis Group, LLC., This research was partially financed by Portuguese Funds through FCT- Fundaçao para a Ciencia e a Tecnologia (PEst-OE/CTE/UI0098/2011) and also by the Spanish Ministry of Science and Innovation (Project CGL2011–2569). This work was supported by FCT grant to AZM (SFRH/BPD/63836/2009).

Theories have been put forward on the etiology of sialoliths; however, a comprehensive understanding of their growth mechanisms is lacking. In an attempt to fill this gap, the current study has evaluated the internal architecture and growth patterns of a set of 30 independent specimens of sialoliths characterized at different scales by computed microtomography and electron microscopy. Tomography reconstructions showed cores in most of the sialoliths. The cores were surrounded by concentric or irregular patterns with variable degrees of mineralization. Regardless of the patterns, at finer scales the sialoliths consisted of banded and globular structures. The distribution of precipitates in the banded structures is compatible with a Liesegang–Ostwald phenomenon. On the other hand, the globular structures appear to arise from surface tension effects and to develop self-similar features as a result of a viscous fingering process. Electron diffraction patterns demonstrated that Ca- and P-based electrolytes crystallize in a structure close to that of hydroxyapatite. The organic matter contained sulfur with apparent origin from sulfated components of secretory material. These results cast new light on the mechanisms involved in the formation of sialoliths.

The aim of this study is to apply X-ray microfocus computed microtomography (μ-XCT), a promising non-destructive 3D microscopy imaging technique, based on measurements of X-ray linear path attenuation coefficient, in order to study a Portuguese travertine, a random heterogeneous geomaterial used in urban heritage constructions. This study evaluates the impact of soluble sulphate salt–induced decay phenomena on texture characteristics at a micrometric scale. This is done to better describing, imaging, measuring and understanding the impact of an artificially induced sulphate-decay process on petrographic/petrophysical properties. A Portuguese travertine was chosen as the object of our study. Its laboratory-induced changes were systematically monitored, using non-destructive techniques, to determine voids (pores + fractures)/matrix fractions and size spectrum evolution based on 3-D images. This investigation demonstrates that the μ-XCT potential constitutes a valid complementary tool when analysing decay processes of complex natural materials in different environmental conditions. It clearly provides suggestive and important qualitative and/or quantitative estimates, at different spatial scales, of environmentally induced stone voids/matrix network spatial structure-texture evolution correlations. Further qualitative/quantitative parameterization assessment and statistical validation will be the next step to be taken on this study., Fundação para a Ciência e a Tecnologia (FCT) através do projeto POCTI\CTA\44940\2002_PORENET e os projetos estratégicos PEstOE/CTE/UI0697/2011 and PEst-OE/CTE/UI0098/2011 (fundos nacionais e europeus - FEDER)

Summary. Many complex systems require that computational models of different nature are used for their sub-systems. The evaluation of the dynamics of each one of these models requires the use of different codes, which in turn use different time integration algorithms. The work presented here proposes a co-simulation environment that uses an integrated memory shared communication methodology between the multibody and finite element codes. The methodology is general being applicable to the dynamic co-simulation of models running in different codes. The benefits and drawbacks of the proposed methodology and of its accuracy and suitability are supported by the application to a real operation scenario of a highspeed catenary-pantograph system for which experimental test data is available.

In the great majority of railway networks the electrical power is provided to the locomotives by the pantograph-catenary system. From the mechanical point of view, the single most important feature of this system consists in the quality of the contact between the contact wire(s) of the catenary and the contact strips of the pantograph. Therefore not only the correct modeling of the catenary and of the pantograph must be achieved but also a suitable contact model to describe the interaction between the two systems must be devised. The work proposed here aims at enhancing the understanding of the dynamic behavior of the pantograph and of the interaction phenomena in the pantograph-catenary system. The catenary system is described by a detailed finite element model of the complete subsystem while the pantograph system is described by a detailed multibody model. The dynamics of each one of these models requires the use of different time integration algorithms. In particular the dynamics of the finite element model of the catenary uses a Newmark type of integration algorithm while the multibody model uses a Gear integration algorithm, which is variable order and variable time step. Therefore, an extra difficulty that arises in study of the complete catenary-pantograph interaction concerns the need for the cos-imulation of finite element and multibody models. As the gluing element between the two models is the contact model, it is through the representation of the contact and of the integration schemes applied for the finite and multibody models that the co-simulation is carried on. The work presented here proposes an integrated methodology to represent the contact between the finite element and multibody models based on a continuous contact force model that takes into account the co-simulation requirements of the integration algorithms used for each subsystem model.

A.J. Anjos*, P. Nolasco**, J.M. Aquino Marques*, F. Cabrita***, M.F.C. Pereira****, A.P. Alves de Matos***** and P.A. Carvalho** *Faculdade de Medicina Dentaria, Universidade de Lisboa, Cidade Universitaria, 1649-003 Lisboa, Portugal **ICEMS, Instituto Superior Tecnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal ***Servico de Cirurgia Maxilo-Facial, Centro Hospitalar de Lisboa Central, R. Jose Antonio Serrano 1150-199 Lisboa, Portugal ****CEGPIST, Departamento de Engenharia Civil, Arquitectura e Georrecursos, Instituto Superior Tecnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal *****Anatomia Patologica, Centro Hospitalar de Lisboa Central - HCC, Rua da Beneficencia 8, 1069-166 Lisboa; Centro de Estudos do Ambiente e do Mar (CESAM/FCUL) - Faculdade de Ciencias da Universidade de Lisboa and Centro de Investigacao Interdisciplinar Egas Moniz (CiiEM), Quinta da Granja , Monte de Caparica, 2829-511 Caparica, Portugal The oral cavity is susceptible to several calcifications such as salivary calculi (sialoliths), dental calculus (tartar) and tonsillar concretions (tonsilloliths). Although several individual studies had been already carried out, a comprehensive morphological and elemental comparison between them is still missing. Sialoliths are most commonly found in the submandibular glands [1] and are composed of regions rich in Ca and P minerals, namely hydroxyapatite, whitlockite and brushite [1], and regions consisting of organic matter with high-sulphur content [1]. These regions are organized in alternating concentric layers [1]. Several bacterial species have also been identified in sialoliths microstructure showing that infection occurs recurrently throughout the stone formation [2]. Generally, tartar presents an inorganic structure rich in Ca and P minerals, such as brushite, octacalcium phosphate, hydroxyapatite and whitlockite, and an organic matrix, mainly constituted by aerobic bacteria and yeast or just anaerobic bacteria [3]. Tonsilloliths occur most commonly on the crypts of the palatal tonsils and are composed of a mixture of organic matter, namely bacterial cells and epithelial debris, as well as inorganic material rich in Ca and P minerals such as hydroxyapatite. Volatile sulphur compounds produced by anaerobic bacteria are usually associated to these, in general, innocuous structures [4]. The current study involved the ultrastructure and chemical characterization of the calcified structures by scanning electron microscopy (SEM) combined with energy dispersive spectroscopy carried out with a JEOL JSM 7001F instrument with an INCA pentaFetx3 Oxford spectrometer operated at 15 kV. Higher resolution characterization has been performed by transmission electron microscopy (TEM) using a H8100 Hitachi instrument operated at 200 kV. SEM samples were prepared following metallographic procedures [1], whereas TEM samples were obtained following standard biological sample preparation procedures [5]. The results show that sialoliths present the most complex structure, with a central core surrounded by concentric layers, while tartar and tonsilloliths do not have a distinctive architecture (Figures 1 (a), 2 (a) and 3 (a). At higher magnifications, layered structures, as well as crystals could be found in sialoliths and tartar (Figures 1 (b) and 2 (b). Bacteria were common in all the calcified structures, although in tonsilloliths their abundance is higher (Figure 3 (b)). All calcifications have similar elemental constitution, with Ca and P, indicating the presence of calcium phosphates (Figures 1 (c), 2 (c) and 3 (c). Sulphur was also found associated with the organic matter in sialoliths and tonsilloliths, though the amounts found in the latter were much smaller than initially expected. Based on the similarities found, new correlations between these calcification will be available. For instance, the mineralization process described in tartar can help understand the similar processes occurring in sialoliths and tonsilloliths, while the association between bacteria and sulphur in tonsilloliths can be a clue for their presence in

Several theories have been put forward regarding the aetiology and pathogenesis of salivary calculi, although a comprehensive understanding of the nucleation and growth mechanisms involved in the formation of these structures is still lacking.In general, sialoliths present one core partially or highly mineralized surrounded by concentric layers of organic and mineralized matter that alternate in succession following a chronologic sequence. The layers consist of fine mineralized strata intercalated with fine organic ones and threaded globular structures with variable degrees of mineralization.The exact mechanism involved in the genesis of sialoliths remains largely unknown, theories defending an initial organic nidus or an initial precipitation of minerals, with subsequent deposition of organic and inorganic layers, can be found in the literature. Nevertheless, it remains object of discussion the etiologic factors responsible for the formation of the first nidus or the initial precipitation, since infection, inflammation of the gland, viscous nature of the mucous secretions or naturally existing sialomicroliths have all have been implicated.Aiming at an exhaustive systematization of salivary calculi morphogenesis, their morphology has been studied by micro-computed tomography (bCT) and scanning electron microscopy (SEM). CCT studies were done on as-extracted dried samples using uCT SkyScan 1172 instrument with a 1.3 Megapixel camera, operated at the maximum available power of the source (10W). Radiographs acquisition was performed with a rotational step in the 0.70-1° range, until a maximum of 180º, with an exposure time in the 3.1-5 s range. Microscopy observations were carried out with backscattered electron (BSE) signals using a JEOL JSM 7001F operated at 15 kV, samples were previously prepared following metallographic procedures.The submandibular and parotid calculi investigated presented similar growth patterns, which can follow either concentric (Figure 1) or perturbed-growth typologies (Figure 2), although in most situations a gradation between them has been found. Nevertheless, a single well-defined core constituted by material with low mineralization was frequently present, supporting the nucleation hypothesis of an initial organic nidus.The combination of TCT with SEM enabled a comprehensive characterization of the sialoliths: (i) the former technique allowed for a precise localization of the core and other morphological features within the calculus volume, while (ii) investigation of details at higher resolution could be achieved with the latter method. However, due to the friable nature of the sialoliths, handling during sample preparation results often in material loss (compare (a) and (b) in both Figures).The work was carried out with financial support of the Portuguese Foundation for Science and Technology through PTDC/SAU-ENB/111941/2009 and PEst-OE/CTM-UI0084/2011 grants.

The safety assessment of old timber structures is an important issue, due to the long-term behaviour of wood and the structural complexity found in some older constructions. If the structure is degraded due to the action of wood-boring insects, the complexity of the analysis increases. The objective of this work was to evaluate the impact of anobiid beetles’ attack on old timber structures. One major difficulty concerns the assessment of the effective strength of timber cross sections with anobiid damage. This happens because beetles’ attack produces a diffuse damage, with a set of tunnels in random directions.Compression parallel to the grain and screw withdrawal tests have been made in pine naturally degraded by anobiids (natural samples – NS) and in pine with artificially bored galleries (artificial samples – AS). 216 samples were tested (97 to screw withdrawal and 119 to compression). The original density of NS is unknown. For AS, 0.7% and 1.4% of lost material was simulated. Screw withdrawal and compression force values were related with density for AS (𝑟2 = 0.52 for compression; 𝑟2 = 0.56 for screw withdrawal). The results show a significant variation between the average results obtained both to the compression (42.9 MPa – AS; 27.2 MPa – NS) and to the pull- out (3.4 KN – AS; 2.2 KN – NS).Although there was an attempt to simulate the degradation by woodworm with the AS, with known density, the test results were significantly different from those obtained for the NS, where the percentage of lost material is unknown, as well as initial density. Thus, knowledge of residual timber density seems to be paramount to know the level of deterioration and the real impact of this on a structure. Further developments on this issue are ongoing.