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The fraction of organic matter present affects the fragmentation behavior of sialoliths; thus, pretherapeutic information on the degree of mineralization is relevant for a correct selection of lithotripsy procedures. This work proposes a methodology for in vivo characterization of salivary calculi in the pretherapeutic context. Sialoliths were characterized in detail by X-ray computed microtomography (μCT) in combination with atomic emission spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Correlative analysis of the same specimens was performed by in vivo and ex vivo helical computed tomography (HCT) and ex vivo μCT. The mineral matter in the sialoliths consisted essentially of apatite (89 vol%) and whitlockite (11 vol%) with average density of 1.8 g/cm3. In hydrated conditions, the mineral mass prevailed with 53 ± 13 wt%, whereas the organic matter, with a density of 1.2 g/cm3, occupied 65 ± 10% of the sialoliths’ volume. A quantitative relation between sialoliths mineral density and X-ray attenuation is proposed for both HCT and μCT.

The on-board identification of ore minerals during a cruise is often postponed until long after the cruise is over. During the M127 cruise, 21 cores with deep-seafloor sediments were recovered in the Trans-Atlantic Geotraverse (TAG) field along the Mid Atlantic Ridge (MAR). Sediments were analyzed on-board for physicochemical properties such as lightness (L*), pH and Eh. Selected samples were studied for mineral composition by X-ray powder diffraction (XRD). Based on XRD data, sediment samples were separated into high-, low- and non-carbonated. Removal of carbonates is a common technique in mineralogical studies in which HCl is used as the extraction agent. In the present study, sequential extraction was performed with sodium acetate buffer (pH 5.0) to remove carbonates. The ratio between the highest calcite XRD reflection in the original samples (Iorig) vs its XRD-reflection in samples after their treatment with the buffer (Itreat) was used as a quantitative parameter of calcite removal, as well as to identify minor minerals in carbonated samples (when Iorig/Itreat &gt, 24). It was found that the lightness parameter (L*) showed a positive correlation with calcite XRD reflection in selected TAG samples, and this could be applied to the preliminary on-board determination of extraction steps with acetate buffer (pH 5.0) in carbonated sediment samples. The most abundant minerals detected in carbonated samples were quartz and Al- and Fe-rich clays. Other silicates were also detected (e.g., calcic plagioclase, montmorillonite, nontronite). In non-carbonated samples, Fe oxides and hydroxides (goethite and hematite, respectively) were detected. Pyrite was the dominant hydrothermal mineral and Cu sulfides (chalcopyrite, covellite) and hydrothermal Mn oxides (birnessite and todorokite) were mineral phases identified in few samples, whereas paratacamite was detected in the top 20 cm of the core. The present study demonstrates that portable XRD analysis makes it possible to characterize mineralogy at cored sites, in particular in both low- and high-carbonated samples, before the end of most cruises, thus enabling the quick modification of exploration strategies in light of new information as it becomes available in near-real time.

The archaeological site of Almaraz is located in the old part of the city of Almada, in the south shore of Tagus River, region of Lisbon. The excavated findings and the radiocarbon dating of the contexts where these were found show an occupation that can in fact be dated from the 8th to the 7th c. BCE period, thus a very early stage of the Phoenician occupation in the Iberian Peninsula. Numerous amphorae sherds were found at Almaraz. A spectroscopic characterization of those ceramics was made and is presented here, to help us understand if they were produced locally, in Lisbon workshops, or imported. Sixteen sherds representative of the thousands found at Almaraz were studied with the use of non-invasive spectroscopies, namely by crossing information from micro-Raman and X-ray fluorescence emission data. X-ray diffraction experiments were also performed. In spite of the fact that no ceramic kilns were found at Almaraz until now, the results point to two major groups of amphorae of local origin: one which used clays of Miocene origin, found on the southern shores of the Tagus River, very close to the Almaraz site, at Palenca (with quartz, anorthite, diopside and hematite). Another group, remarkably different, made use of clays of Pliocene origin also from the Tagus Estuary, the Fontainhas clay source (where quartz, anorthite, muscovite and hematite were found).

A favourable electronic structure, together with a high abundance of pyrite (FeS2) in the Earth's crust, make this sulfide a promising material for thermoelectric applications. However, the experimental work published to date underlines a challenging scenario, with FeS2 presenting systematically small power factors. Knowing that sulfur vacancies are a key aspect for controlling the electronic transport properties of FeS2, this work focuses on the preparation of pyrite by hot-pressing and entails a careful characterization of its microstructure, chemical composition, thermal stability, and electrical transport properties. Dense pellets (>90% of the theoretical density) were obtained, consisting mostly of pyrite with trace amounts of Fe7S8. Different hot-pressing conditions led to similar chemical compositions, with no significant lattice distortions. Pyrite proved to be thermally stable up to 400 °C under an inert atmosphere. Analysis of the electronic band structure and density of states by density functional theory implies a p-type semiconductivity. However, measurements of Seebeck coefficient indicated n-type semiconductivity for pyrite produced by this experimental procedure. The highest power factor measured in this work, 0.23 μW K−2 m−1, is still far from what can be considered a promising value for thermoelectric materials, but different ways of improving it are discussed.

São estudadas as rochas ornamentais Butterfly Beige, Butterfly Gold e Butterfly Green correspondentes a quartzo sienitos com hiperstênio que são exploradas em Barra de São Francisco-Espírito Santo, Brasil. O objetivo é analisar os efeitos estéticos, bem como quantificá-los, depois de submetidas à exposição de temperaturas elevadas a partir de análises comparativas das imagens, das cores e das respectivas características petrográficas. Os valores para os coeficientes de correlação (r) entre as rochas, já nos primeiros 200ºC, mostram descaracterizações moderadas, sendo as rochas bastante afetadas pela temperatura. As alterações causadas pela ciclagem térmica somada à umidade aceleram o processo de oxidação do Fe. Além disso, por histerese, a ciclagem implica a geração de microfissuras e o alargamento dos planos de clivagem dos minerais, bem como ofusca os contatos entre eles, facilitando a percolação de fluidos (água) e aumentando o grau de oxidação do Fe ao mesmo tempo em que facilita a disseminação do Fe(OH)2. Frente aos resultados obtidos, sugere-se que as rochas estudadas (principalmente a variedade Green) sejam utilizadas em revestimentos de ambientes internos e que fontes de calor, como o sol, em revestimentos externos, podem acelerar o processo de modificação das cores em função da presença de minerais ferro-magnesianos e, principalmente, do Fe (OH)2 passíveis de oxidação

The recovery of lithium from hard rock minerals has received increased attention given the high demand for this element. Therefore, this study optimized an innovative process, which does not require a high-temperature calcination step, for lithium extraction from lepidolite. Mechanical activation and acid digestion were suggested as crucial process parameters, and experimental design and response-surface methodology were applied to model and optimize the proposed lithium extraction process. The promoting effect of amorphization and the formation of lithium sulfate hydrate on lithium extraction yield were assessed. Several factor combinations led to extraction yields that exceeded 90%, indicating that the proposed process is an effective approach for lithium recovery. info:eu-repo/semantics/publishedVersion

Black crusts on different substrates (carbonate and silicate stones, cement-based mortar and carbonate detrital deposits) in urban environments were characterized microscopically by analysing their morphologies and compositions. The objective of this article is to study the interaction between the substrate and the crust and the influence of the environmental conditions on the crust development. On the one hand, the internal structure and morphology of each sample were evaluated with stereo and scanning electron microscopies. On the other hand, the black crust composition was accessed by X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy in backscattered electron mode combined with energy dispersive x-ray spectroscopy. The results of these analytical techniques provided interesting information about the composition and the mineralogical phases present in the collected black crusts. In most of the cases, gypsum was detected as the main component exhibiting different habits. Calcite was also detected in all the evaluated gypsum black crusts; its presence was attributed to different origins. The substrate-crust interaction was also evaluated, contributing to distinguish different crust development processes in relation to the substrate. In carbonate substrates (limestones, mortar and carbonate detrital deposits), it was detected a continuous diffuse boundary related to the replacement of Ca-carbonate by Ca-sulphate, while this boundary was significantly more defined for the granitic stone. This study shows that the substrate, the presence of different construction materials, (e.g. mortars), the motor exhaust particulate substances and the concentrations of atmospheric pollutants, the marine influence as well as biological or other anthropogenic compounds are decisive factors in the development of the black crust. Some ideas about the establishment of conservation strategies are also shown.

Mechanical activation in order to improve lithium recovery from a lepidolite ore concentrate was investigated. The concentrate was mechanically activated using different milling times and the effect on the resulting products was evaluated by X-ray powder diffraction, FTIR spectroscopy, TG-DTG analysis, SEM and particle size analysis by laser diffraction. The mechanical activation leads to lepidolite amorphization and concomitant improvement of the reactivity by sulfuric acid digestion and water leaching. About 85% of Li recovery was achieved when the concentrate was activated for 15 min and afterwards digested at 165 °C, during 4 h, using an acid/concentrate ratio of 650 g/kg. Li recoveries above 70% were reached even using digestion temperatures lower than 100 °C. However, to increase recovery, temperatures over 140 °C are more suitable. Results obtained showed that is possible to apply a low temperature technology for recovering Li from hard rock minerals, using mechanical activation.

São Domingos sulfide mine was shut down more than 50 years ago leaving behind eroded and depositional surfaces due to acid mine drainage (AMD). The aim of this study was to assess six selected sites subjected to AMD, considered phytotoxic regions characterized by vegetation scarcity. Two main criteria, nature and composition of soluble fractions and total chemistry of surficial products related to jarosites presence, enabled to set up an overall dichotomy between superficial proximal/discharge and distal/sedimentation areas. Wet and dry sieving results comparison revealed that samples have a predominant sandy texture and lithic (phyllite, quartzite and volcanic country rocks) composition. Quartz, and subordinate feldspar enrichment is also detected in the coarse silt fraction. The results also suggest that the materials under study, when subjected to the local torrential hydrologic regime, have a high mechanical vulnerability, facilitating erosion and mud transport, both critical for vegetation support, and triggering contamination transfer and dispersion. The vicinity and ground-level surfaces of discharging areas are enriched in the jarosite group minerals whereas the sedimentation ones present hypersaline aluminous tendency. The formation of jarosite is considered as an efficient positive environmental contribution to metals and metalloids sequestration/immobilization. The remediation/revegetation solutions to be adopted in each location must have into consideration these differentiating aspects.

The lithium extraction from a lepidolite concentrate using roasting, followed by water leaching, was studied. Several alternative additives were initially tested. The use of sodium and calcium sulfates as additives was evaluated in more detail. The influence of some process variables, namely the roasting time, roasting temperature and the additive/concentrate mass ratio, was studied applying a design of experiments. The lithium extraction was modelled and the fitted and validated model was used to optimize the process response. The increase in the additive/concentrate mass ratio, roasting time and temperature seems to result in solid state reactions and transformations that lead to phase, morphological and particle size distribution modifications, which were assessed by XRPD, SEM, and particle size analyses. In this process, lithium sodium sulfate formation constitutes a crucial step enabling the Li water leaching. High lithium extractions were estimated for several combinations of factors. At 850...

The number of published studies related to the optimization of lithium extraction from low-grade ores has increased as the demand for lithium has grown. However, no study related to the kinetics of the concentration stage of lithium-containing minerals by froth flotation has yet been reported. To establish a factorial design of batch flotation experiments, we conducted a set of kinetic tests to determine the most selective alternative collector, define a range of pulp pH values, and estimate a near-optimum flotation time. Both collectors (Aeromine 3000C and Armeen 12D) provided the required flotation selectivity, although this selectivity was lost in the case of pulp pH values outside the range between 2 and 4. Cumulative mineral recovery curves were used to adjust a classical kinetic model that was modified with a non-negative parameter representing a delay time. The computation of the near-optimum flotation time as the maximizer of a separation efficiency (SE) function must be performed with caution. We instead propose to define the near-optimum flotation time as the time interval required to achieve 95%–99% of the maximum value of the SE function.

A Cu 12 Sb 3.6 Bi 0.4 S 10 Se 3 glass was prepared by melt spinning and crystallized by heat treatments at selected temperatures, the total preparation procedure taking less than one day. The sample characterization by powder X-ray diffraction, scanning and transmission electron microscopy complemented with EDS indicate the formation of compact materials, with a tetrahedrite relative weight fraction higher than 90% when treated at temperatures close to the crystallization peaks (∼200° C). Selenium enters the tetrahedrite structure, while bismuth precipitates in submicron and nanosized spherical shape phases depleted in copper and enriched in antimony, sulfur and selenium (when compared with the matrix composition). The characterization of electrical transport properties (electrical resistivity and Seebeck coefficient) indicate a behavior similar to that obtained by other methods on Cu 12 Sb 4 S 13 , with a maximum power factor of ∼400 μW/K 2 m at room temperature.

The construction sector consumes 95% of the total production of gypsum due to its multiple applications. Gypsum plaster is one of the most common indoor coating material (pastes and mortars), but it can also be used in prefabricated products like plasterboards, blocks and decorative elements. Gypsum waste recycling provides a solution to an important environmental problem from the use of gypsum plaster, which is the generation of large amounts of wastes at different phases (production, construction, rehabilitation and demolition). This paper studies two different replacement alternatives of natural gypsum: Flue Gas Desulphurization (FGD) gypsum and gypsum waste obtained from industrial plasterboard production. The influence of the previous types, amounts of waste (25, 50, 75 and 100 wt%) and different heating temperatures (100 °C, 150 °C and 180 °C) and processes on the workability of gypsum plasters is evaluated and discussed, based on a microstructure analysis using XRD and SEM techniques. This research highlights the feasibility, in terms of workability, of using Gypsum Plasterboard Waste (GPW), without any heating process, as a replacement gypsum in plasters. Despite the fact that a higher amount of water was necessary in the production of the mixes, a good workability was achieved. On the other hand, the unfeasibility of using unheated FGD as a constituent of plasters was demonstrated. However, a good performance, in terms of workability, of the FGD was obtained when the powder was subjected to a heating process at 180 °C during 6 h.

The oldest kilns producing tin glaze wares discovered in the region of Lisbon were located in the south shore of Tagus river at Santo Antonio da Charneca (SAC) and Mata da Machada (MM). Firing this type of pottery from the fourth quarter of the 15th century to mid-16th century, they were located about 20 km away from central Lisbon. Many other examples of ceramics produced in Lisbon workshops from that period are also known and exist in museums or archaeological collections, in spite of the fact that only one kiln dated from that period was found in Lisbon until now. Therefore, the spectroscopic characterization of ceramics found in Lisbon archaeological contexts (attributed to Lisbon workshops) – and also from SAC or MM – was needed and was performed here. Sherds representative of these faience production centres in the Lisbon region dated from the 16th/17th centuries were studied with the use of non-invasive spectroscopies, namely micro-Raman, Ground State Diffuse Reflectance Absorption (GSDR) and X-ray fluorescence emission (XRF). X-ray diffraction (XRD) experiments were also performed. Also clays were collected both in the North and South shores of the river Tagus, as much as possible from the same clay sources as used in the initial workshops. The obtained results evidence a clear similarity in the pastes of the pottery of the Lisbon region, quartz, gehlenite and diopside (or augite) being the major components. Clays are from Miocene origin, but differences between the ceramic pastes were detected pointing to the use of several clay sources. The spectroscopic trend exhibited at SAC and MM pottery is remarkably different, quartz being the major component of those pastes, and clays are from Pliocene origin.

Lithium extraction from hard-rock ores has regained importance due to the increased demand for this metal to supply the growing battery market. Therefore, several studies have been focused on the lithium extraction from ores, however, leaching and purification steps are sparsely studied. Thus, the objective of this study was to evaluate the main factors affecting the water leaching step and the subsequent purification operations for lithium recovery from a lepidolite concentrate, which was processed by mechanical activation and sulphuric acid digestion. In the leaching step, among the variables studied, only one, the leaching temperature, showed a significant effect on the lithium extraction, taking into account the range of values tested. Thus, the recommended operating value for the leaching time and the L/S ratio is the minimum, while for the leaching temperature is 50°C. After optimizing the leaching operation, the purification of the leachate, by neutralization, was thoroughly performed by efficient removal of impurities (Fe, Al, Mn and Ca), allowing to obtain lithium carbonate as final product, as well as other relevant by-products, such as rubidium and potassium alums. info:eu-repo/semantics/publishedVersion

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.

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.

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.

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