Ray Fluorescence Spectrometry Research Articles

“Mining” the herbarium for hyperaccumulators: Discoveries of nickel and zinc (hyper)accumulation in the genus Noccaea (Brassicaceae) through X‐ray fluorescence herbarium scanning

AbstractX‐ray fluorescence spectroscopy (XRF) is a relatively new method for non‐destructive elemental analysis of herbarium material that meets the scientific interest in being capable of discovering new hyperaccumulator plant species. Since the genus Noccaea (Brassicaceae family) is known to be one of the most numerous in term of the hyperaccumulator plant species it contains, especially those that hyperaccumulate Ni, the herbarium material available worldwide represents a great resource for expanding our knowledge of their elemental profiles. In this first systematic XRF scanning of herbarium specimens of the genus Noccaea, a total of 794 specimens from the collection of the National Museum of Natural History in Paris (MNHN) were analyzed, and the raw values obtained were corrected using regression formulas against inductively coupled plasma atomic emission spectroscopy data. Hyperaccumulation of Ni was detected in 90 specimens covering 21 taxa, with Ni concentrations reaching up to 48,700 mg kg−1 in Noccaea cappadocica, an ultramaficophyte from Syria. Zinc concentrations above the hyperaccumulation threshold were found in 210 specimens covering 23 taxa, most of which belonged to different subspecies of Noccaea caerulescens, with the highest concentration reaching up to 56,200 mg kg−1 in N. caerulescens subsp. caerulescens. Although the accumulation of Ni and Zn is contrasting in most of the specimens studied, in 10 specimens, predominantly belonging to N. caerulescens, simultaneous hyperaccumulation of Ni and Zn was found. This study also revealed previously unknown hyperaccumulation of Ni in several Noccaea taxa, as well as a simultaneous hyperaccumulation of Ni and Zn that needs to be confirmed by further experimental and field studies.

Synthesis and characterization of silica xerogel and aerogel from rice husk ash and pulverized beach sand via sol-gel route

The high cost and toxicity associated with the use of orthosilicates as silica precursors drive growing interest in an environmentally friendly and cost - efficient natural silica source. Rice husk (a biomass) and beach sand are both natural and non - toxic and the extraction of silica from each using sodium hydroxide makes the process green for the production of nanosilica gels (xerogel and aerogel) via the sol – gel route. The gels from the ash of rice husk and pulverized beach sand were dried by the use of a laboratory oven and supercritical extraction methods. The structures of the gels were studied through X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), scanning electron microscopy (SEM), X - ray fluorescence (XRF) spectroscopy and Fourier transform infrared (FTIR) spectroscopic analyses. XRF spectroscopy revealed silicon in its oxide form as the prominent element with low levels of trace elements concentrations. XRD results showed the crystalline nature of the prepared silica. TEM images confirmed the crystalline and nanometric structures of the streak - free xerogel and aerogel. SAED confirmed that the gels were polycrystalline with no streaks. SEM monographs showed varied globes of fine surfaces indicating the high level of purity of the gels. FTIR showed the absorption peaks of the silanol-OH bond and Si-O-Si vibration, confirming the gels as nanometric structures. The high yield, crystalline nature, purity and crystallographic features of the produced silica suggest rice husk ash and pulverized beach sand as alternative silica sources for the production of silica gels nanoparticles with potential applications in biomedical field, nanofiltration and as additive for improving the strength of materials.

In English

Hybrid carbons/metals/metal (metalloid) oxides composites could be effective adsorbents for low– and high–molecular weight compounds, polar and nonpolar, gaseous and liquid. The presence of metal nanocrystallites and carbon nanostructures could provide catalytic properties in redox reactions. For more effective use of hybrid composites, their morphological, structural, textural, and adsorption characteristics should be appropriate for target applications and, therefore, well controlled. Therefore, the aim of this study was to synthesize carbon/metal/silica nanostructured composites with varied content of metal (Ni) to control the mentioned characteristics. Precipitated silica Sipernat 50 was selected as a substrate. Potato starch was used as a carbon precursor. Nickel nitrate (Ni(NO3)2·6H2O) of varied amounts was used as a precursor of Ni nanoparticles reduced upon the starch carbonization. After the starch carbonization and Ni reduction, a set of C/Ni/silica samples was studied using atomic force microscopy, X–ray diffraction, X–ray fluorescence spectroscopy, nitrogen and p-nitrophenol adsorption, thermogravimetry, and Raman spectroscopy. The presence of nickel phase results in the formation of smaller but denser packed char nanoparticles. Estimation of possible contribution of pores accessible for nitrogen molecules in silica globules and outer surface of carbon/Ni particles suggests that the carbon phase is porous that provides a significant part of the specific surface area of the composites. Amorphous silica and char phases are characterized by the presence of certain nuclei of radius (R) < 1 nm and 2 nm < R < 10 nm estimated from the XRD patterns using full peak profile analysis with a self–consistent regularization procedure. Ni crystallites are of several sizes, since particle size distributions include two–three peaks in the range of 3–13 nm in radius. The Raman spectra show that the main changes with increasing Ni content are characteristic to sp3 carbon structures (D line) in contrast to the sp2 structures (G line). The pore size distributions (both differential and incremental) demonstrate complex changes in a broad size range due to increasing Ni content in composites. As a whole, changes in the Ni content in nanostructured C/Ni/silica composites allow one to control the morphological, structural, and textural characteristics of the whole materials.

XRFitProc: A novel web‐based x‐ray fluorescence fitting system

AbstractX‐ray fluorescence (XRF) spectroscopy is a widely used technique in microscopy, spanning from biology to cultural heritage applications. Its purpose is to characterize qualitatively and quantitatively, the presence of elemental species in a sample. This is accomplished through fitting the acquired data to a Gaussian model, identifying which XRF lines and associated elements are present. As a result, 2D images of cumulative count‐rate maps associated with each element are produced. This procedure is not trivial to apply efficiently in a workflow, as it requires the user to be able to set a series of parameters (e.g., beam energy, background subtraction, etc.) on top of selecting XRF lines under investigation. Furthermore, users should easily and swiftly be able to change setup parameters and evaluate the effects on the results. In the present work, we introduce a web‐based application that allows users to load the XRF data, setup a fit and inspect the results interactively within a simple graphical user interface (GUI) that enables easily going back and forth from setup to result inspection. In particular, it is possible to quickly view the count‐rate maps and curve fitting simultaneously, on any single pixel spectra present in the images. The web‐application can be accessed locally by a web‐browser, but runs remotely on a cloud, freeing from the need of installing any software and will be made publicly available in the near future. At present, it has been designed to work on both conventional and sparse XRF data such as Compressive Sensing, in an embarrassingly parallel manner.

Magnesium-based alloys analyses by nuclear techniques

Magnesium-based alloys have been proposed for used in temporary biomaterials in the applications that request their biocompatibility and degradability. Analyses of these alloys are of great interest to verify if their element composition is within the product specification and also to evaluate the impurities that may cause toxic effects to the human health or influence in their corrosion processes. In this study, nuclear techniques of neutron activation analysis (NAA) and wavelength dispersive X ray fluorescence spectrometry (WD XRFS) were applied in the analyses of two magnesium-based alloys: commercially pure magnesium (CP-Mg) and AZ31 alloy. The NAA procedure consisted of irradiating aliquots of sample and synthetic element standards followed by measurements using a HGe detector and the WD XFRS was carried out using the Model RIX 3000 X-ray spectrometer. In the CP-Mg sample several element impurities were quantified. In the AZ31 alloy, the alloying element mass fractions were within the product specification and the impurities of As, La, Na and Sb were also quantified. Nickel and sulfur were quantified only by WD XFRS. The Horwitz method was a good parameter to evaluate the repeatability of the results in Al, Mg, Mn and Zn determinations. In conclusion, the results indicated the viability of using NAA and WD XFRS in the analyses of magnesium-based materials mainly due its multielement determinations, precision of the results, quantification of elements in a wide range of mass fractions and the lack of need for sample dissolution.

Study on Catalytic Reduction of Methylene Blue Using Silver Nanoparticles Synthesized via Green Route

Abstract: We have synthesized silver nanoparticles using silver nitrate and Azadirachta indica (Neem) aqueous leaf extract at room temperature. The method used for synthesis is simple, rapid, environmental free and do not involve toxic chemicals. The terpenoids and flavonoids available in neem plant leaf extract act as both capping and reducing agents. The synthesized nanoparticles are characterized UV Visible spectroscopy, X ray diffraction analysis and fluorescence spectroscopy. The synthesized AgNPs are used for study of the catalytic degradation of methylene blue by sodium borohydride (NaBH4) in presence of AgNPs as catalyst. The 100% degradation of methylene blue was achieved by (NaBH4+AgNPs) in just 08 minutes which highlights the efficient catalytic activity of AgNPs.

Simple Co-precipitation synthesis and characterization of magnetic spinel NiFe2O4 nanoparticles

Nickel ferrite nanoparticles were synthesized using Iron (III) nitrate and nickel nitrate as the starting materials along with the hydrazine hydrate via co-precipitation process and the final product obtained calcined at 700 °C. The structural and optical properties of the synthesised product were determined using various characterization techniques viz. UV–visible spectrometry, X-ray diffractometer (XRD), transmission electron microscopy (TEM), Field Emission Scanning Electron Microscopy (FE-SEM) and vibrating sample magnetometer (VSM). The NiFe2O4 nanoparticles showed absorption at ∼ 356 nm corresponds to band gap of 4.1 eV. The elemental analysis was carried out using X – ray Fluorescence (XRF) and Energy Dispersive Spectroscopy (EDS). The synthesized NiFe2O4 were 10–15 nm in size, and exhibited high saturation magnetization value of 72.66 emu/g.

Fusion of Gamma-rays and portable X-ray fluorescence spectral data to measure extractable potassium in soils

The detection and mapping of plant-extractable potassium (Ka) using proximal soil sensing and data fusion (DF) techniques are essential to optimise K2O fertiliser application, improve crop yield, and minimise environmental and financial costs. This work evaluates the potential of combined use of portable gamma ray and x-ray fluorescence spectroscopy for in field detection and mapping of Ka. After subjected to various pre-processing methods, spectral data were split into calibration (75%) and validation (25%) sets, and single sensor and DF models were developed using partial least squares regression (PLSR). Maps of Ka were used to present spatial variability of potassium across an 8.4 ha Voor de Hoeves target field, in Flanders, Belgium. Results showed that the gamma-ray PLSR model using wet soils had greater predictive ability with coefficient of determination (R2) = 0.71, ratio of performance deviation (RPD) = 1.89, root mean square error (RMSE) = 31.7 mg kg-1, and ratio of performance to interquartile range (RPIQ) = 2.36 than the corresponding wet-XRF PLSR model (R2 = 0.61, RPD = 1.64, RMSE = 48.8 mg kg-1 and RPIQ = 1.84). The DF PLSR model on wet soils, resulted in a more accurate Ka predictive ability (R2 = 0.75, RPD = 2.03, RMSE = 31.3 mg kg-1 and RPIQ = 2.79), compared to the individual gamma ray or XRF sensors in wet soils. The best accuracy was obtained with XRF spectrometer using dry samples (R2 = 0.77, RPD = 2.14, RMSE = 26.5 mg kg-1 and RPIQ = 3.39). All Ka prediction maps showed spatial similarity to the corresponding measured maps in the target field. In conclusion, since DF increased the Ka prediction accuracy compared to the single sensor models using wet soils, it is recommended to be adopted in future studies as a potential solution for Ka measurement, mapping, and ultimately for site-specific K2O fertilisation management. The XRF analysis of dry spectra is recommended as the best method for accurate measurement of Ka.

Investigation of the protective suitability of a dental fluorinated varnish by means of X Ray fluorescence and Raman spectroscopy

Background and aimEvaluating the protective effect in human enamel of a fluorinated varnish after enduring a citric acid erosive challenge. MethodsAn in vitro model was developed considering the intraoral environment, human saliva and acid erosive procedures. The evaluation of the enamel specimens was undertaken through the direct analysis of enamel by means of Raman spectroscopy and Energy Dispersive X Ray Fluorescence (EDXRF). Ten tooth specimens per group were analysed during three stages: 1- before treatment; 2- After varnish (treatment group) or toothpaste (control) application; 3- After citric acid cycle. Additionally, Particle Induced Gamma Ray emission (PIGE) was used to gauge the fluorine uptake by enamel after the application of the varnish (stage 2). Results were presented as mean and standard deviation with ANOVA and Tukey post hoc performed considering a significance level of 0.05. ResultsA significant (p < 0.05) higher Ca levels were detected in treatment group at stage 2 (37.4 ± 0.4 w/w%) and 3 (37.1 ± 0.1) when compared to the control group. After varnish application in treatment group, depolarization ratios were significant lower (p < 0.05) and anisotropy were significant higher (p < 0.05), however no differences were detected in FWHM. ConclusionsThe use of a fluorinated dental varnish suggests a protective effect for human enamel against dental erosion demineralization process which was detectable in an in vitro model.

REGULATION OF THE STRUCTURE OF HONEY DURING ITS LONG-TERM STORAGE

The article describes a new method of treating crystallised honey and the characteristics of the obtained liquid honey stored for a long period of at least 1 year. It has been shown that a new method of low- temperature isothermal accelerated processing in a microwave reactor MWR-SPR allows melting crystallised honey to the liquid state. This accelerates its decrystallisation by 250 times compared to the known method that involves heat transfer. The properties of crystals of solid and liquid honey have been investigated and their structures have been compared after rapid low-temperature, isothermal treatment with the help of the microwave technology of ultrahigh frequencies at 50°C, for 60s. The number and size of pollen particle in honey are reduced by 10 times, and the size of glucose and sucrose crystals after processing is 5 times as small. The method of angular distribution of the laser beam has shown that the average size of sugar macromolecules in the treated honey decreases by 2 times as compared with crystallised honey. It has been proved that the suggested low-temperature, isothermal, accelerated treatment in a microwave reactor preserves a high diastase number in Gothe units (10–11), and the content of hydroxymethylfurfural does not exceed 3–6mg/kg honey. The results of X- ray fluorescence spectroscopy have confirmed that the chemical and elemental and oxide composition of honey after treatment is almost unchanged. Analysis of chemical and biological oxygen consumption shows that in the liquid honey samples, after melting by the suggested method, the biochemical activity of honey only reduced twofold, but it is far less than when honey is dissolved by the traditional heat transfer method. All this has a positive effect on stabilising liquid honey after its dissolution and on its stability during long-term (up to 1 year) storage. Based on dissolved, liquid, caramelised honey, a chewing gum has been developed to prevent and treat periodontal disease in dentistry. The chewing gum has been clinically tested and has proved highly effective in 72% of patients with gingivitis, gum disease, and periodontitis.

Adsorption competition study between chromate and phosphate from their solutions by total reflection X ray fluorescence spectrometry

This paper explores the application of Total Reflection X‐Ray Fluorescence (TXRF) spectrometry for chromate (CrO42−) and phosphate (PO43−) determinations in synthetic solutions after their adsorption onto dolomite. The competition between both contaminants is also evaluated. Adsorption processes are considered an inexpensive, non‐contaminating alternative for retaining, on a selected substrate, a variety of pollutants present in different effluents. For a specific adsorbent, an important factor to be taking into account is the competition among different possible species. Variables such as concentration, temperature, ionic strength and pH were evaluated. Dolomite, a natural mineral based on calcium and magnesium carbonates, was employed as adsorbent. TXRF is an efficient, fast trace element analytical technique and requires only minimum specimen preparation, for that reason is suitable for this study. The experiments were carried out in batch systems; pH and ionic strength of the solution were measured and controlled. The results obtained in individual systems (phosphate‐dolomite or chromate‐dolomite) indicate a 70.5% for phosphate and 22.7% for chromate removal. The adjustment of the ionic strength had no influence on the removal of the anions. According to this study, the adsorption of chromate was reduced to 14% when the pH increased; this fact did not affect phosphate removal. The removal of both ions increased at pH under than 6. The presence of both ions at different concentrations did not change the removal value for the phosphate, whereas the removal of chromate was almost null, indicating a strong interference of the phosphate in the removal of chromate.

A simple microanalytical method for trace elemental determination in plutonium samples using energy dispersive X-ray fluorescence

A simple microanalytical method for trace elemental determinations in plutonium (Pu) solution samples was developed using Energy Dispersive X- Ray Fluorescence (EDXRF) spectrometry. A very small sample volume (200 μL) of Pu solution was taken for analysis and the major matrix Pu was separated using the extractant, Tri n-Butyl Phosphate (TBP), in 4 M HNO3 medium. Aliquot of 5 μL of the aqueous phase containing only the trace elements were deposited on a thin transparent mylar film inside the PVC (Poly Vinyl Chloride) EDXRF sample container and dried in ambient atmosphere inside a radioactive fume hood. After drying, the container was sealed with PVC lids. Two pure Pu solutions spiked with different trace elements having concentration of 6.25 and 23.25 μg/mL, were analyzed with RSD (Relative Standard Deviation) of 6.6 and 4.2% (1 σ, n = 3), and the average deviation from the expected values calculated on the basis of sample preparation were 8.9 and 6.6%, respectively. The developed methodology requires small amount of sample, extractant, and therefore generates less radioanalytical waste. Moreover, due to the requirement of small amount of sample, sealed inside a PVC container, the measurements could be carried out in ambient atmosphere without putting the instrument inside glove box. Further, the simple instrumentation of EDXRF, made this methodology very much ideal for the routine analysis of plutonium based samples.

Application of Fusion sample preparation X Ray Fluorescence Spectrometry in the Identification of Solid Waste Characteristic of Imported Coated Fibre Cloth

The composition of imported coated fibre cloth was quickly identified by fusion sample preparation X-ray fluorescence spectrometry. Na2O, MgO, Al2O3, SiO2, P2O5, SO3, K2O, CaO, TiO2, Cr2O3, MnO, Fe2O3, NiO, CuO, ZnO, As2O3, SrO, ZrO, CdO, BaO, PbO in the matrix of the coated fibre cloth were determined. In this paper, the technology of direct melting of flake sample is studied. The method of pre-oxidation is that the sample piece is obliquely placed on the inner wall of crucible to increase the air circulation space and remove the organic matter and halide in a short time. The 66.5:33.5 mixed flux was used as the flux, and LiBr was used as the release agent. The temperature was about 1050 °C, and the time was about 17 min. The problem of melting of inorganic fibre and flux melt was found and solved. The calibration curve is constructed by silicate rock, bauxite, cement and other reference materials and high-purity reagents. The matrix effect correction adopts the variable theoretical α influence coefficient method, and B2O3 represents the unmeasured components as the elimination item. The maximum Al2O3, SiO2, CaO curves of this method are 84.4%, 91.5%, 62.6%, respectively. The Cr, Ni, Cu, As, Cd, Pb curve range of harmful elements is greater than 0.005%-0.33%; 21 curves have good linearity. R2 divided by BaO equals 0.997 and the rest are greater than 0.9993; the detection limit of harmful elements is less than 15 mg·g−1; precision relative standard deviation (n=11) principal component is less than 0.5%, and trace component is less than 15%; after comparison of standard substances and standard methods, the results are consistent. Accuracy of methods is good, and it can quickly identify the content of the main elements of the coated fibre cloth and provide a strong support for the subsequent identification of solid waste characteristic.

Food Supplements for Weight Loss: Risk Assessment of Selected Impurities.

Nowadays, food supplements are widely consumed, often without any medical supervision. In this study, 25 food supplements for weight loss, randomly purchased from five different suppliers in the European Union, were analysed by Wavelength Dispersive X ray Fluorescence spectrometry (WDXRF). The aim of this study was the risk assessment of trace elements and the mixture of elements present in food supplements for weight loss. The obtained Hazard Index (0.11) showed no potential risk of non-carcinogenic effects to human health. However, since humans are frequently exposed by different routes and/or sources to toxic metals, the additional consumption of these products may cause potential toxicological risks that cannot be ignored. In one analysed food supplement (FS), the simultaneous presence of Pb and Mn in high concentrations was detected. In two, FS chromium concentrations were above the reference daily dose. Unconformities were detected between the labelled and the detected values, which emphasises the misinformation of labels. This highlights the need for a deeper surveillance of food supplements.

MRS, EDXRF and GC–MS analysis for research on the ritual and funerary areas of Cerro de los Vientos (Baeza, Jaén, Spain). Native and Eastern Mediterranean influences

This paper is about the results obtained from the physico-chemical analysis of the Orientalizing (7th century BC) archaeological materials retrieved from the ritual and funerary areas of the site Cerro de los Vientos (Baeza, Jaén, Spain). The samples under study are native tradition and Phoenician ceramic vessels, and beads of several colours. The analysis used Micro Raman Spectroscopy (MRS) with portable and laboratory equipments, Energy Dispersive X Ray Fluorescence (EDXRF) and Gas Chromatography-Mass Spectrometry (GC–MS). Joint use of these techniques allowed to examine the interaction between the native community of Cerro de los Vientos and the Eastern Mediterranean influence by populations of Phoenician origins.Use of MRS and EDXRF helped identify the mineral and elemental composition of the decorations of the native and Phoenician ceramic vessels, and also of the red and blue beads. Hematite, goethite, amorphous carbon and graphite were recorded in the native pottery. Hematite and manganese oxide were recorded in the Phoenician pottery. The red beads were made of carnelian, a variety of chalcedony that is not found in the Iberian Peninsula. The blue beads were made of glass paste.GC–MS contents analysis identified beeswax in most vessels, both native and Phoenician. The beeswax in native and Phoenician vessels from the area for the funerary feast and in the funerary urns laid in the graves leads to an interpretation in terms of hydromel consumption during feasts and offerings of honey in urns.

A case study on pollution and a human health risk assessment of heavy metals in agricultural soils around Sinop province, Turkey

In the present study, the concentration levels of heavy metals such as Cr, Fe, Ni, Cu, Zn, As and Pb in soil samples collected from 88 sampling locations around Sinop Province, Turkey were measured using energy dispersive X–ray fluorescence spectroscopy (EDXRF). To interpret and to evaluate the pollution status and distribution of heavy metals in soil, metal pollution parameters such as enrichment factor (EF), geo–accumulation index (Igeo), pollution factor (CF) and pollution load index (PLI) and geo–spatial distribution patterns were used. The mean concentrations of Cr, Fe, Ni, Cu, Zn, As, and Pb were found to be 194.73, 39,848.57, 85.02, 43.19, 65.10, 5.66, and 17.01 mg/kg, respectively. Results indicated that the mean concentrations of Cr, Ni, As, and Pb exceeded the world crustal average, with the exception of Fe, Cu, and As. Multivariate analysis results showed that Cr, Ni, Zn, As, and Pb levels in the investigated region were highly influenced by anthropogenic inputs such as agricultural practices. According to the health risk assessment model introduced by USEPA to evaluate the human health risks, the non–carcinogenic risk for children was above the threshold level, but low for adults. Total potential carcinogenic health risks for both children and adults in the study area were in acceptable range. Overall, when health risks are evaluated, it shows that children are more susceptible to non–carcinogenic and carcinogenic health effects of trace metals compared to adults.

A Review on Nanotechnology: Analytical Techniques Use and Applications

The combination of nanotechnology with molecular biology, information technology and instrumentation, is opening the door to a new industrial age. The aim of this review article is to summarize the current knowledge of nanotechnology in synthesizing, identifying and characterization of nanomaterials using analytical techniques. Physical and chemical approach synthesis of nanomaterials befalls challenges in the development of analytical techniques used to characterize them. The major techniques include: Transmission Electron Microscopy, Scanning Electron Microscopy, Atomic Force Microscopy, Dynamic Light Scattering, X ray Photoelectron Spectroscopy, X-ray Diffraction, Single Phase Inductively Coupled Plasma Mass Spectroscopy, X ray Fluorescence Spectroscopy, Auger Electron Spectroscopy, X ray Absorption Fine Structure, Capillary Electrophoretic Separations, Magnetic nano particles coupled HPLC and Dynamic light scattering. Nanomaterials have been characterized for the extensive potential applications in optics, electronics, magnetics, and catalysts; chemical sensing, biomedicine, micro reactor, and they have been applied in food, biological, environmental and pharmaceuticals uses. In spite of the extended use of nano particles in diverse consumer products, there is a great concern over the unexpected impact or effects on humans due to exposure.

Monte Carlo simulation of portable X-ray fluorescence setup: Non-invasive determination of gold leaf thickness in indo-Portuguese panel paintings

In this work, we present the combined use of in situ X ray Fluorescence spectroscopy and Monte Carlo simulation using PENELOPE code for the completely non-invasive determination of gold leaf thickness in artworks using lead white as mordant. The methodology used is based on the detection of different characteristic lines of Pb in the X ray fluorescence spectra, attenuated trough the gold leaves, and determining the thickness of gilding by comparing their attenuation. Firstly, this methodology was calibrated using model samples of simple stratigraphy, namely pure Au leafs of 1, 2 and 2.5 μm thickness covering a Pb infinitely thick sheet. The modelled X ray setup was then used to study the gilding thickness of three panel paintings belonging to the Museum of Christian Art in Old Goa (India): two paintings, from the 18th century, concerning to the same series but different themes: Our Lady of Sorrows (MoCA1) and Our Lady of Seven Sorrows (MoCA2), and a third painting entitled Monstrance (MoCA3), from the 17th century. These panel paintings were analyzed to understand the differences and similarities between techniques, according to the time/epoch and technique of its manufacture. The obtained values for MoCA2 tend to be slightly lower than for MoCA1, however, the t student test revealed that the differences were not statistically different (p = .37). Regarding the MoCA3 painting, the average thickness was determined to be statistically different (p < .001) and higher than for the other two paintings. These results emphasize the use of different techniques concerning gold leaf beating. In the 17th century painting it was verified the use of a thicker gold leaf while in the group of the 18th century gold leaf was thinner and manufactured with a similar thickness in both paintings. These results are in consonance with the accuracy of leaf beating technology, increasing with the experience acquired during the ages.

Técnicas de ultrasonido para la caracterización de vidrios volcánicos

Contexto: La caracterización geoquímica de materiales arqueológicos de obsidiana o vidrio volcánico, utilizado en el pasado para la confección de herramientas líticas, permite trazar su procedencia geológica e inferir formas de interacción y rangos de movilidad de antiguas poblaciones humanas. La caracterización de la composición geoquímica de la obsidiana por análisis de activación neutrónica permite determinar con un buen grado de certidumbre su procedencia; sin embargo, es una técnica costosa y destructiva, por lo que no es recomendable para piezas arqueológicas. Otras técnicas más accesibles como la fluorescencia de rayos X o la espectrometría de masas con plasma acoplado inductivamente han sido utilizadas con éxito para esta aplicación pero con un mayor nivel de incertidumbre. En este trabajo se busca asistir al problema por medio del uso de otras técnicas no destructivas que pudieran ser aplicables al patrimonio arqueológico.&#x0D; Método: Se exploraron las propiedades mecánicas de una muestra de obsidiana a través de métodos de ultrasonido. Se evaluaron la velocidad de fase y atenuación de ondas longitudinales, y se cuantificó la densidad de las muestras por picnometría de gases, que posibilita determinar los módulos elásticos dinámicos. Además, se repitieron las mismas mediciones en probetas de vidrio de manufactura industrial.&#x0D; Resultados: Se observó que la velocidad, la densidad y el módulo longitudinal son mayores para la muestra de vidrio industrial que para la muestra de obsidiana. Por otro lado, la atenuación resultó ser mayor para el caso de la obsidiana y se observó una mayor dependencia con la frecuencia.&#x0D; Conclusiones: Los resultados obtenidos demuestran la capacidad del método para distinguir entre materiales con composición química diferente, por lo que sería viable para ser aplicado a estudios arqueológicos. Además, las diferencias observadas en la atenuación muestran que el método también es sensible a la microestructura del material, por lo que aportaría información no accesible mediante técnicas convencionales de arqueometría.

Uncovering the links between osteoporosis and diabetes

Introduction: Using an animal model for osteopenia to describe the distribution of Lead (Pb) throughout the body, we have reported that ovariectomized animals had significantly lower serum osteocalcin (OC) levels and higher, although nonsignificant, serum C-terminal peptide-bound crosslinks of collagen (CTX) levels than intact animals [1]. Here we present unpublished data on concentrations of elements of interest (Ca, Cl, Fe, K, Na and Pb) in hard and soft tissues of the same animals, to uncover the links between osteoporosis and diabetes. The model makes it feasible to investigate such links, therefore the appropriateness of this approach is not only warranted but also justified by the 3RS principle for the use of animals in research. Materials and methods: The animal study was approved by the Ethics Committee of ISCSEM and was conducted following the Portuguese Law and EU Directive 2010/63/EU, in a licensed animal facility. Two groups of adult female Wistar rats of the same age were considered: normal intact rats (n = 7); and OVX animals (n = 7) ovariectomized between the 11th and 12th week of age. From age 6-months on, all animals received the same dose of Pb acetate in water (500 ppm) for 6 months. Tissues collected for analysis included lumbar vertebrae and femora bones, as well as blood and liver. The concentration of elements of interest in hard and soft tissues was determined by Wavelength Dispersive X Ray Fluorescence (WDXRF) spectroscopy, using a 4kW commercial spectrometer (S4 Pioneer, Bruker AXS). Multivariate analysis of variance (MANOVA) was used in group comparisons, given the multiple correlations between elemental concentrations. Results: MANOVA methods show that OVX animals have significantly higher liver Cl, Na and Ca concentrations, whereas normal animals show significantly higher liver Pb and K concentrations, with observed power of 91.0%. Significantly lower serum OC levels were observed in the OVX group, with observed power of 72.7%, with no differences between groups for CTX levels. Lower Ca content was strongly suggested for trabecular bone of OVX animals. Discussion and conclusions: Significant differences in hepatic Ca concentration between OVX and normal animals suggest that Ca signalling mechanisms regulating gluconeogenesis, through modulation of hormones such as glucagon, insulin, vasopressin and adrenalin [2,3], may occur differently in the two groups. Moreover, since extracellular concentrations of cations such as K and Na markedly affect the hormonal activity effects on gluconeogenesis [4], the observed differences in the hepatic concentrations of such elements between the groups may further increase differences in gluconeogenesis in the two groups. Therefore, we postulated that bone turnover changes may impact on gluconeogenesis, which launched the basis for another research project linking osteoporosis to diabetes, nearly concluded in our laboratory.