“Identification of inorganic and organic microliths in kidney sections by laser microprobe mass analysis (LAMMA)”. Verbueken A, Verpooten G, Nouwen E, de Broe M, Van Grieken R, (1986)
Keywords: P3 Proceeding; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Laboratory Experimental Medicine and Pediatrics (LEMP)
|
“Localisation of lead in tissues of poisoned rats by laser microprobe mass analysis (LAMMA)”. Vandeputte D, Verbueken A, Jacob W, de Broe M, Van Grieken R, (1986)
Keywords: P3 Proceeding; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Laboratory Experimental Medicine and Pediatrics (LEMP)
|
“The microanalysis of individual atmospheric aerosol particles by electron, proton and laser microprobe”. Artaxo P, Van Grieken R, Watt F, Jaksic M, (1990)
Keywords: P3 Proceeding; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
|
“Laser microprobe mass analysis (LAMMA) of parathyroid glands from dialysis patients”. Verbueken AH, Van de Vyver FL, Nouwen EJ, Roels F, de Broe ME, Van Grieken RE page 443 (1987).
Keywords: H3 Book chapter; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Laboratory Experimental Medicine and Pediatrics (LEMP)
|
“Hyperfine electric parameters calculation in Si samples implanted with 57Mn\rightarrow57Fe”. Abreu Y, Cruz CM, Pinera I, Leyva A, Cabal AE, van Espen P, Van Remortel N, Physica: B : condensed matter 445, 1 (2014). http://doi.org/10.1016/J.PHYSB.2014.03.028
Abstract: Nowadays the electronic structure calculations allow the study of complex systems determining the hyperfine parameters measured at a probe atom, including the presence of crystalline defects. The hyperfine electric parameters have been measured by Mossbauer spectroscopy in silicon materials implanted with Mn-57 ->,Fe-57 ions, observing four main contributions to the spectra. Nevertheless, some ambiguities still remain in the Fe-57 Mossbauer spectra interpretation in this case, regarding the damage configurations and its evolution with annealing. In the present work several implantation environments are evaluated and the Fe-57 hyperfine parameters are calculated. The observed correlation among the studied local environments and the experimental observations is presented, and a tentative microscopic description of the behavior and thermal evolution of the characteristic defects local environments of the probe atoms concerning the location of vacancies and interstitial Si in the neighborhood of Fe-57 ions in substitutional and interstitial sites is proposed. (C) 2014 Elsevier B.V. All rights reserved
Keywords: A1 Journal article; Particle Physics Group; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/J.PHYSB.2014.03.028
|
“Ferrihydrite precipitation in groundwater-fed river systems (Nete and Demer river basins, Belgium) : insights from a combined Fe-Zn-Sr-Nd-Pb-isotope study”. Dekov VM, Vanlierde E, Billström K, Gatto Rotondo G, van Meel K, Darchuk L, Van Grieken R, et al, Chemical geology 386, 1 (2014). http://doi.org/10.1016/J.CHEMGEO.2014.07.023
Abstract: Two groundwater-fed river systems (Nete and Demer, Belgium) carry red suspended material that settles on the river bed forming red sediments. The local aquifer that feeds these river systems is a glauconite-rich sand, which provides most of the dissolved Fe to the rivers. The solid component of these systems, i.e., the red suspended material and sediments, has a simple mineralogy (predominantly ferrihydrite), but shows a complex geochemistry pointing out the different processes contributing to the river chemistry: (1) the red sediments have higher transition metal (excluding Cu) and detrital element (e.g., Si, Al, K, Rb, etc.) concentrations than the red suspended matter because of their longer residence time in the river and higher contribution of the background (aquifer) component, respectively; (2) the red suspended material and sediments have inherited their rare earth element (REE) patterns from the aquifer; (3) the origin of Sr present in the red suspended matter and red sediments is predominantly marine (i.e., Quaternary calcareous rocks), but a small amount is geogenic (i.e., from detrital rocks); (4) Pb in both solids originates mostly from anthropogenic and geogenic sources; (5) all of the anthropogenic Pb in the red suspended material and sediments is hosted by the ferrihydrite; (6) Nd budget of the red riverine samples is controlled by the geogenic source and shows little anthropogenic component; (7) the significant Fe- and Zn-isotope fractionations are in line with the previous studies. Their fractionation patterns do not correlate, suggesting that the processes controlling the isotope geochemistry of Fe and Zn are different: oxidation/reduction most likely governs the Fe-isotope fractionation, whereas adsorption/desorption or admixing of anthropogenic sources controls the isotope fractionation of Zn.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/J.CHEMGEO.2014.07.023
|
“Optimized energy dispersive X-ray fluorescence analysis of atmospheric aerosols collected at pristine and perturbed Amazon Basin sites”. Arana A, Loureiro AL, Barbosa HMJ, Van Grieken R, Artaxo P, X-ray spectrometry 43, 228 (2014). http://doi.org/10.1002/XRS.2544
Abstract: Elemental composition of aerosols is important to source apportionment studies and to understand atmospheric processes that influence aerosol composition. Energy dispersive X-ray fluorescence spectroscopy was applied for measuring the elemental composition of Amazonian atmospheric aerosols. The instrument used was a spectrometer Epsilon 5, PANalytical B. V., with tridimensional geometry that reduces the background signal with a polarized X-ray detection. The measurement conditions were optimized for low-Z elements, e. g. Mg, Al, Si, that are present at very low concentrations in the Amazon. From Na to K, our detection limits are about 50% to 75% lower than previously published results for similar instrument. Calibration was performed using Micromatter standards, except for P whose standard was produced by nebulization of an aqueous solution of KH2PO4 at our laboratory. The multi-element reference material National Institute of Standards and Technology-2783 (air particulate filter) was used for evaluating the accuracy of the calibration procedure of the 22 elements in our standard analysis routine, and the uncertainty associated with calibration procedures was evaluated. The overall performance of the instrument and validation of our measurements were assessed by comparison with results obtained from parallel analysis using particle-induced X-ray emission and another Epsilon 5 spectrometer. The elemental composition in 660 samples collected at a pristine site in the Amazon Basin and of 1416 samples collected at a site perturbed by land use change was determined. Our measurements show trace elements associated with biogenic aerosols, soil dust, biomass burning, and sea-salt, even for the very low concentrations as observed in Amazonia. Copyright (C) 2014 John Wiley & Sons, Ltd.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1002/XRS.2544
|
“Methods, fluxes and sources of gas phase alkyl nitrates in the coastal air”. Dirtu AC, Buczyńska AJ, Godoi AFL, Favoreto R, Bencs L, Potgieter-Vermaak SS, Godoi RHM, Van Grieken R, Van Vaeck L, Environmental monitoring and assessment 186, 6445 (2014). http://doi.org/10.1007/S10661-014-3866-7
Abstract: The daily and seasonal atmospheric concentrations, deposition fluxes and emission sources of a few C3C9 gaseous alkyl nitrates (ANs) at the Belgian coast (De Haan) on the Southern North Sea were determined. An adapted sampler design for low- and high-volume air-sampling, optimized sample extraction and clean-up, as well as identification and quantification of ANs in air samples by means of gas chromatography mass spectrometry, are reported. The total concentrations of ANs ranged from 0.03 to 85 pptv and consisted primarily of the nitro-butane and nitro-pentane isomers. Air mass backward trajectories were calculated by the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model to determine the influence of main air masses on AN levels in the air. The shorter chain ANs have been the most abundant in the Atlantic/Channel/UK air masses, while longer chain ANs prevailed in continental air. The overall mean N fluxes of the ANs were slightly higher for summer than those for winter-spring, although their contributions to the total nitrogen flux were low. High correlations between AN and HNO2 levels were observed during winter/spring. During summer, the shorter chain ANs correlated well with precipitation. Source apportionment by means of principal component analysis indicated that most of the gas phase ANs could be attributed to traffic/combustion, secondary photochemical formation and biomass burning, although marine sources may also have been present and a contributing factor.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Toxicological Centre
DOI: 10.1007/S10661-014-3866-7
|
“Characterization of the ionic and particulate systems in the reservoir”. Godoi RHM, Lima Bittencourt AV, Hirata PY, Jafelicci Junior M, dos Reis Neto JM, Van Grieken R page 143 (2014).
Keywords: H2 Book chapter; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
|
“Label-free impedance aptasensor for major peanut allergen Ara h 1”. Trashin S, De Jong M, Breugelmans T, Pilehvar S, De Wael K, Electroanalysis 27, 32 (2015). http://doi.org/10.1002/ELAN.201400365
Abstract: The peanut allergen Ara h 1 belonging to the vicilin family of seed storage proteins is known to be a suitable marker for peanut detection in foods. In the present work, we suggest an electrochemical detection of Ara h 1 using a recently selected 80-base DNA aptamer. The detection strategy relies on insulation effect of a bulky protein captured by an immobilized aptamer. The electrodes were modified by the aptamer and characterized using electrochemical impedance spectroscopy (EIS). The aptamer surface density and analytical parameters of the calibration curves for Ara h 1 were compared with the system prepared with thrombin binding aptamer (TBA) and operated in the same conditions.
Keywords: A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Applied Electrochemistry & Catalysis (ELCAT)
Times cited: 10
DOI: 10.1002/ELAN.201400365
|
“Improved calculation of displacements per atom cross section in solids by gamma and electron irradiation”. Pinera I, Cruz CM, Leyva A, Abreu Y, Cabal AE, van Espen P, Van Remortel N, Interactions With Materials And Atoms 339, 1 (2014). http://doi.org/10.1016/J.NIMB.2014.08.020
Abstract: Several authors had estimated the displacements per atom cross sections under different approximations and models, including most of the main gamma- and electron-material interaction processes. These previous works used numerical approximation formulas which are applicable for limited energy ranges. We proposed the Monte Carlo assisted Classical Method (MCCM), which relates the established theories about atom displacements to the electron and positron secondary fluence distributions calculated from the Monte Carlo simulation. In this study the MCCM procedure is adapted in order to estimate the displacements per atom cross sections for gamma and electron irradiation. The results obtained through this procedure are compared with previous theoretical calculations. An improvement in about 10-90% for the gamma irradiation induced dpa cross section is observed in our results on regard to the previous evaluations for the studied incident energies. On the other hand, the dpa cross section values produced by irradiation with electrons are improved by our calculations in about 5-50% when compared with the theoretical approximations. When thin samples are irradiated with electrons, more precise results are obtained through the MCCM (in about 20-70%) with respect to the previous studies. (C) 2014 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Engineering sciences. Technology; Particle Physics Group; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/J.NIMB.2014.08.020
|
“Degradation process of lead chromate in paintings by Vincent van Gogh studied by means of spectromicroscopic methods : part 5 : effects of nonoriginal surface coatings into the nature and distribution of chromium and sulfur species in chrome yellow paints”. Monico L, Janssens K, Vanmeert F, Cotte M, Brunetti BG, van der Snickt G, Leeuwestein M, Plisson JS, Menu M, Miliani C, Analytical chemistry 86, 10804 (2014). http://doi.org/10.1021/AC502841G
Abstract: The darkening of lead chromate yellow pigments, caused by a reduction of the chromate ions to Cr(III) compounds, is known to affect the appearance of several paintings by Vincent van Gogh. In previous papers of this series, we demonstrated that the darkening is activated by light and depends on the chemical composition and crystalline structure of the pigments. In this work, the results of Part 2 are extended and complemented with a new study aimed at deepening the knowledge of the nature and distribution of Cr and S species at the interface between the chrome yellow paint and the nonoriginal coating layer. For this purpose, three microsamples from two varnished paintings by Van Gogh and a waxed low relief by Gauguin (all originally uncoated) have been examined. Because nonoriginal coatings are often present in artwork by Van Gogh and contemporaries, the understanding of whether or not their application has influenced the morphological and/or physicochemical properties of the chrome yellow paint underneath is relevant in view of the conservation of these masterpieces. In all the samples studied, microscopic X-ray fluorescence (mu-XRF) and X-ray absorption near edge structure (mu-XANES) investigations showed that Cr(III)-based alteration products are present in the form of grains inside the coating (generally enriched of S species) and also homogeneously widespread at the paint surface. The distribution of Cr(III) species may be explained by the mechanical friction caused by the coating application by brush that picked up and redistributed the superficial Cr compounds, likely already present in the reduced state as result of the photodegradation process. The analysis of the XANES profiles allowed us to obtain new insights into the nature of the Cr(III) alteration products, that were identified as sulfate-, oxide-, organo-metal-, and chloride-based compounds. Building upon the knowledge acquired through the examination of original paint samples and from the investigation of aged model paints in the last Part 4 paper, in this study we aim to characterize a possible relation between the chemical composition of the coating and the chrome yellow degradation pathways by studying photochemically aged model samples covered with a dammar varnish contaminated with sulfide and sulfate salts. Cr speciation results did not show any evidence of the active role of the varnish and added S species on the reduction process of chrome yellows.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 6.32
Times cited: 25
DOI: 10.1021/AC502841G
|
“Young Anthony van Dyck revisited : a multidisciplinary approach to a portrait once attributed to Peter Paul Rubens”. Van der Stighelen K, Janssens K, van der Snickt G, Alfeld M, Van Beneden B, Demarsin B, Proesmans M, Marchal G, Dik J, Art matters : international journal for technical art history 6, 21 (2014)
Abstract: Part of the collection of the Rubens House in Antwerp is a portrait of young Anthony van Dyck, alternatively attributed to Peter Paul Rubens and his pupil Anthony van Dyck. In order to reconstruct the genesis of the portrait in a manner that improves upon past investigations, a number of high-end technological methods, such as X-radiography, X-ray computer tomography, mammographic tomosynthesis and macroscopic X-ray fluorescence, have been employed to render the overpainted layers visible again. The results of the interdisciplinary examinations of the portrait of the youthful Van Dyck are impressive. The combined results allow the later additions to be peeled away until the original composition can be reached. Several pentimenti are easily discernible and refer to a rather immature hand that makes the authorship of Peter Paul Rubens very unlikely. What emerges is a portrait of an ambitious young man with a luxuriant head of hair and a slightly turned-up collar. The hat and cape were added later. The facial features are more recognisable and the execution of the bold curls points irrefutably in the direction of Anthony van Dyck as the author of his own portrait.
Keywords: A3 Journal article; Art; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
|
“Physico-chemical fate of chromium compounds in the lung sheep model”. Perrault G, Dufresne A, Strati G, McNeil M, Michaud D, Baril M, Bégin R, Labbé, J, Larivière P, Eeckhaoudt S, Van Grieken R, Journal of toxicology and environmental health 44, 247 (1995). http://doi.org/10.1080/15287399509531958
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1080/15287399509531958
|
“The elemental chemistry of sediments in the Nainital lake, Kumaun Himalaya, India”. Das BK, Singh M, Van Grieken R, The science of the total environment 168, 85 (1995). http://doi.org/10.1016/0048-9697(95)04242-S
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/0048-9697(95)04242-S
|
“Composition of aerosols over the Laptev, the Kara, the Barents, the Greenland and the Norwegian seas”. Shevchenko VP, Lisitzin AP, Kuptzov VM, Ivanov GI, Lukashin VN, Martin JM, Rusakov VY, Safarova SA, Serova VV, Van Grieken R, van Malderen H page 7 (1995).
Keywords: H3 Book chapter; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
|
“Study of a unique 16th century Antwerp majolica floor in the Rameyenhof castle's chapel by means of X-ray fluorescence and portable Raman analytical instrumentation”. Van de Voorde L, Vandevijvere M, Vekemans B, Van Pevenage J, Caen J, Vandenabeele P, van Espen P, Vincze L, Spectrochimica acta: part B : atomic spectroscopy 102, 28 (2014). http://doi.org/10.1016/J.SAB.2014.10.007
Abstract: The most unique and only known 16th century Antwerp majolica tile floor in Belgium is situated in a tower of the Rameyenhof castle (Gestel, Belgium). This exceptional work of art has recently been investigated in situ by using X-ray fluorescence (XRF) and Raman spectroscopy in order to study the material characteristics. This study reports on the result of the analyses based on the novel combination of non-destructive and portable instrumentation, including a handheld XRF spectrometer for obtaining elemental information and a mobile Raman spectrometer for retrieving structural and molecular information on the floor tiles in the Rameyenhof castle and on a second, similar medallion, which is stored in the Rubens House museum in Antwerp (Belgium). The investigated material, majolica, is a type of ceramic, which fascinated many people and potters throughout history by its beauty and colourful appearance. In this study the characteristic major/minor and trace element signature of 16th century Antwerp majolica is determined and the pigments used for the colourful paintings present on the floor are identified. Furthermore, based on the elemental fingerprint of the white glaze, and in particular on the presence of zinc in the tiles – an element that was not used for making 16th century majolica – valuable information about the originality of the chapel floor and the two central medallions is acquired. (C) 2014 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Cultural Heritage Sciences (ARCHES)
DOI: 10.1016/J.SAB.2014.10.007
|
“Photocatalytic carbon oxidation with nitric oxide”. Liao L, Heylen S, Vallaey B, Keulemans M, Lenaerts S, Roeffaers MBJ, Martens JA, Applied catalysis : B : environmental 166, 374 (2015). http://doi.org/10.1016/J.APCATB.2014.11.051
Abstract: The photocatalytic oxidation of carbon black on TiO2 using nitric oxide as an oxidizing agent was investigated. Layer-wise deposited carbon and TiO2 powder was illuminated with UVA light in the presence of NO at parts per million concentrations in dry and hydrated carrier gas at a temperature of 150 degrees C. Carbon was photocatalytically converted mainly into CO2, and NO mainly into N-2. Carbon oxidation rates of 7.2 mu g/h/mgTiO(2) were achieved in the presence of 3000 ppm NO. Under these experimental conditions in the absence of molecular oxygen, formation of surface nitrates causing TiO2 photocatalyst deactivation is suppressed. Addition of water enhances surface nitrate formation and catalyst deactivation. NO and carbon particulate matter are air pollutants emitted by diesel engines. Elimination of soot collected on a diesel particulate filter through oxidation is a demanding reaction requiring temperatures in excess of 250 degrees C. The present study opens perspectives for a low-temperature regeneration strategy for the diesel particulate filter that simultaneously performs DeNO(x) reactions. (C) 2014 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 9.446
Times cited: 5
DOI: 10.1016/J.APCATB.2014.11.051
|
“Virtual underpainting reconstruction from X-ray fluorescence imaging data”. Anitha A, Brasoveanu A, Duarte MF, Hughes SM, Daubechies I, Dik J, Janssens K, Alfeld M, , 1239 (2011)
Keywords: P1 Proceeding; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
|
“Improvement in the coating homogeneity in electrosynthesized Rh structured catalysts for the partial oxidation of methane”. Benito P, Monti M, de Nolf W, Nuyts G, Janssens K, et al, Catalysis today 246, 154 (2015). http://doi.org/10.1016/J.CATTOD.2014.10.003
Abstract: The precipitation of Rh/Mg/Al and Rh/Al hydroxides on the surface of FeCrAlloy foams by a base electrogeneration method was investigated to improve the properties of the deposited film (homogeneity and composition) and therefore the performances of the structured catalysts, obtained by calcination, in the Catalytic Partial Oxidation of CH4 to syngas. The work focussed on decreasing current gradients within open-cell foam cylinders by increasing the number of electrical contacts from 1 to 3 points to promote a more homogeneous precipitation of the hydroxides. Electrochemical and catalytic tests as well as SEM/EDS and mu-XRFIXRD analyses allowed to correlate the effect of the number of electrical contact points with materials properties. Lastly, syntheses were performed on Pt plates to study the effect of the electrical behaviour and shape of the support on the composition of the film. A more homogeneous coating of the foam surface was achieved by adopting a configuration with 3 contact points since the reduction of nitrates and water molecules that generates the basic media in the vicinity of the support was enhanced. Layer thicknesses up to 5-15 mu m were deposited; however, the sequential precipitation of a film with composition closer to the expected one and a layer enriched in Al and Rh (outer layer) was not avoided. The improvement in the coating gave rise to enhanced performances for a sample prepared at -1.1 V for 3000 s. Contrarily, the low adherence of the outer layer in a sample prepared at -1.2 V for 2000 s during both calcination and catalytic tests may be responsible of the unexpected decrease in catalytic performances. The same sequential precipitation was observed by performing the syntheses on Pt plates, showing that the electrical nature the support did not play a key role on this phenomenon. (C) 2014 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 4.636
Times cited: 14
DOI: 10.1016/J.CATTOD.2014.10.003
|
“Mitigation strategies for radiation damage in the analysis of ancient materials”. Bertrand L, Schoeeder S, Anglos D, Breese MBH, Janssens K, Moini M, Simon A, Trends in analytical chemistry 66, 128 (2015). http://doi.org/10.1016/J.TRAC.2014.10.005
Abstract: The study of materials in cultural heritage artifacts and micro-samples benefits from diagnostic techniques based on intense radiation sources, such as synchrotrons, ion-beam accelerators and lasers. While most of the corresponding techniques are classified as non-destructive, investigation with photons or charged particles entails a number of fundamental processes that may induce changes in materials. These changes depend on irradiation parameters, properties of materials and environmental factors. In some cases, radiation-induced damage may be detected by visual inspection. When it is not, irradiation may still lead to atomic and molecular changes resulting in immediate or delayed alteration and bias of future analyses. Here we review the effects of radiation reported on a variety of cultural heritage materials and describe the usual practice for assessing short-term and long-term effects. This review aims to raise awareness and encourage subsequent research activities to limit radiation side effects.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 8.442
Times cited: 35
DOI: 10.1016/J.TRAC.2014.10.005
|
“Examination of historical paintings by state-of-the-art hyperspectral imaging methods : from scanning infra-red spectroscopy to computed X-ray laminography”. Legrand S, Vanmeert F, van der Snickt G, Alfeld M, de Nolf W, Dik J, Janssens K, Heritage science 2, 13 (2014). http://doi.org/10.1186/2050-7445-2-13
Abstract: The development of advanced methods for non-destructive selective imaging of painted works of art at the macroscopic level based on radiation in the X-ray and infrared range of the electromagnetic spectrum are concisely reviewed. Such methods allow to either record depth-selective, element-selective or species-selective images of entire paintings. Camera-based full field methods (that record the image data in parallel) can be discerned next to scanning methods (that build up distributions in a sequential manner by scanning a beam of radiation over the surface of an artefact). Six methods are discussed: on the one hand, macroscopic X-ray fluorescence and X-ray diffraction imaging and X-ray laminography and on the other hand macroscopic Mid and Near Infrared hyper- and full spectral imaging and Optical Coherence Tomography. These methods can be considered to be improved versions of the well-established imaging methods employed worldwide for examination of paintings, i.e., X-ray radiography and Infrared reflectography. Possibilities and limitations of these new imaging techniques are outlined.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1186/2050-7445-2-13
|
“Identification of artificial orpiment in the interior decorations of the Japanese tower in Laeken, Brussels, Belgium”. Vermeulen M, Sanyova J, Janssens K, Heritage science 3, Unsp 9 (2015). http://doi.org/10.1186/S40494-015-0040-7
Abstract: In this paper, we used a multi-technique approach in order to identify the arsenic sulfide pigment used in the decorative panels of the Japanese tower in Laeken, Belgium. Our attention was drawn to this particular pigment because of its relatively good conservation state, despite its known tendency to fade over time when exposed to light. The pigment was used with different painting techniques, bound with oil and urushi in the lacquers and with an aqueous binder in the mat relief panels. In the latter case it is always applied as an underlayer mixed with ultramarine blue. This quite unusual pigment mixture also shows a good state of preservation. In this study, the orpiment used for the Japanese tower has been identified as an amorphous arsenic sulfide glass (AsxSx) with the aid of light microscopy, PLM, SEM-EDX and Raman microscopy. The pigment features different degrees of As4S4 monomer units in its structure, also known as realgar-like nano-phases. This most likely indicates different synthesis processes as the formation of these As4S4 monomers is dependent of the quenching temperature (Tq) to which the artificial pigment is exposed during the preparation phase.
Keywords: A1 Journal article; Art; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Times cited: 17
DOI: 10.1186/S40494-015-0040-7
|
“A large area full-field EDXRF imaging system based on a THCOBRA gaseous detector”. Silva ALM, Carvalho ML, Janssens K, Veloso JFCA, Journal of analytical atomic spectrometry 30, 343 (2015). http://doi.org/10.1039/C4JA00301B
Abstract: By taking advantage of the attractive features in terms of gain, position and energy resolution of the 2D-THCOBRA detector, a new large area Full-Field X-ray Fluorescence Imaging (FF-XRFI) system for EDXRF imaging applications was developed. The proposed FF-XRFI system has an active area of 10 x 10 cm(2) and can be used to examine macroscopic samples with a moderately good energy resolution (< 1.6 keV FWHM at 8 keV) and a suitable spatial resolution (similar to 500 mu m FWHM). This combination of characteristics allows us to record elemental distribution maps from the surface of different sample types by combining image and energy information. Two different approaches were used for X-ray optics, one based on a single pinhole and another based on a parallel multiple-hole collimator. To illustrate the system capabilities, some sample examples were imaged and studied.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 3.379
Times cited: 11
DOI: 10.1039/C4JA00301B
|
“Thermodynamic and experimental study of the degradation of the red pigment mercury sulfide”. Radepont M, Coquinot Y, Janssens K, Ezrati J-J, de Nolf W, Cotte M, Journal of analytical atomic spectrometry 30, 599 (2015). http://doi.org/10.1039/C4JA00372A
Abstract: The red pigment mercury sulfide, called cinnabar or vermilion, is well known to suffer from an alteration giving rise to a grey, grey-white or black color at the surface of degraded works of art. This phenomenon can dramatically affect the esthetical value of artworks. This work aims at assessing the factors (light, halides) influencing the instability of red mercury sulfide and understanding (by combining thermodynamic and experimental approaches) the chemical equilibria governing the formation and evolution of the different degradation compounds. From the thermodynamic study of the Hg-S-Cl-H2O system, it was concluded that Hg(0), Hg3S2Cl2, and Hg2Cl2 can be formed from the reaction of alpha-HgS with ClO(g). In the second part, the artificial ageing experiments presented were carried out on model samples following the conditions assessed in the first part, in order to reproduce natural ageing observed on red mercury sulfide. Similarly to degradation compounds detected on original works of art, mercury chlorine compounds such as calomel (Hg2Cl2) and corderoite (alpha-Hg3S2Cl2) were identified on the surface of alpha-HgS model samples, when exposed to light and a sodium hypochlorite solution. Sulfates were detected as well, and more particularly gypsum (CaSO4 center dot 2H(2)O) when Ca was originally present in the model sample. The relationship between color and composition is discussed as well.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 3.379
Times cited: 26
DOI: 10.1039/C4JA00372A
|
“Full spectral XANES imaging using the Maia detector array as a new tool for the study of the alteration process of chrome yellow pigments in paintings by Vincent van Gogh”. Monico L, Janssens K, Alfeld M, Cotte M, Vanmeert F, Ryan CG, Falkenberg G, Howard DL, Brunetti BG, Miliani C, Journal of analytical atomic spectrometry 30, 613 (2015). http://doi.org/10.1039/C4JA00419A
Abstract: A combination of synchrotron radiation (SR) micro X-ray fluorescence (m-XRF) and XRF mode X-ray absorption near edge structure (XANES) measurements at the Cr K-edge already allowed us to establish that the photo-reduction of chromates to Cr(III) compounds is the cause of darkening of chrome yellow pigments (PbCr1-xSxO4, 0 <= x <= 0.8) in a number of paintings by Vincent van Gogh and in corresponding artificially aged paint models. A silicon drift detector (SDD) was employed to record the Cr-K XRF radiation in these X-ray micro beam-based measurements. However, in view of the limited count rate capabilities and collection solid angle of a single device, m-XRF and m-XANES employing single element SDDs (or similar) are primarily suited for collection of spectral data from individual points. Additionally, collection of XRF maps via point-by-point scanning with relatively long dwell times per point is possible but is usually confined to small areas. The development of the 384 silicon-diode array Maia XRF detector has provided valuable solutions in terms of data acquisition rate, allowing for full spectral (FS) XANES imaging in XRF mode, i.e., where spectroscopic information is available at each pixel in the scanned map. In this paper, the possibilities of SR Cr K-edge FS-XANES imaging in XRF mode using the Maia detector are examined as a new data collection strategy to study the speciation and distribution of alteration products of lead chromate-based pigments in painting materials. The results collected from two micro-samples taken from two Van Gogh paintings and an aged paint model show the possibility to perform FS-XANES imaging in practical time frames (from several minutes to a few hours) by scanning regions of sample sizes of the same order (more than 500 mm). The sensitivity and capabilities of FS-XANES imaging in providing representative chemical speciation information at the microscale (spatial resolution from similar to 2 to 0.6 mm) over the entire scanned area are demonstrated by the identification of Cr(OH) 3, Cr(III) sulfates and/or Cr(III) organometallic compounds in the corresponding phase maps, as alteration products. Comparable Cr-speciation results were obtained by performing equivalent higher spatial resolution SR m-XRF/single-point m-XANES analysis using a more conventional SDD from smaller regions of interest of each sample. Thus, large-area XRF mode FS-XANES imaging (Maia detector) is here proposed as a valuable and complementary data collection strategy in relation to “ zoomed-in” high-resolution m-XRF mapping and single-point m-XANES analysis (SDD).
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 3.379
Times cited: 28
DOI: 10.1039/C4JA00419A
|
“Strategies for processing mega-pixel X-ray fluorescence hyperspectral data: a case study on a version of Caravaggio's painting Supper at Emmaus”. Alfeld M, Janssens K, Journal of analytical atomic spectrometry 30, 777 (2015). http://doi.org/10.1039/C4JA00387J
Abstract: Technical progress in the fields of X-ray sources, optics and detectors is constantly enhancing the pace of data acquisition in XRF imaging. This enlarges the size of the hyperspectral datasets and the number of their sub-parts. This paper describes the challenges in processing large XRF datasets featuring several million pixels/spectra and the strategies developed to overcome them. During the investigation of historical paintings by scanning macro-XRF the main challenges are the correct identification of all spectral features in a dataset and its timely processing. For the identification of spectral features different approaches are discussed, i.e. the use of sum spectra, maximum pixel spectra and of chi(2)(r) maps. For the time-efficient, artefact-free evaluation of XRF imaging data, different software packages are evaluated and intercompared (AXIL, PyMCA, GeoPIXE and the in-house written datamuncher). The process of data evaluation is illustrated on a large dataset (3.4 MPixels) acquired during the investigation of a version of Caravaggio's Supper at Emmaus (143 x 199.5 cm(2)). This 17th century painting is currently the largest object entirely scanned with macroscopic XRF.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 3.379
Times cited: 67
DOI: 10.1039/C4JA00387J
|
“Elemental composition of PM2.5 in Araraquara City (Southeast Brazil) during seasons with and without sugar cane burning”. Silva FS, Godoi RHM, Tauler R, de André, PA, Saldiva PHN, Van Grieken R, de Marchi MRR, Journal of environmental protection 6, 426 (2015). http://doi.org/10.4236/JEP.2015.65041
Abstract: Particulate matter with an aerodynamic diameter below 2.5 μm (PM2.5), present in polluted air, has been associated with a large spectrum of health impairments, mainly because of its deep deposition into the lungs. Araraquara City (Southeast Brazil) is surrounded by sugar-cane plantations, which are burned to facilitate the harvesting; this process causes environmental pollution due to the large amounts of soot that are released into the atmosphere. In this work, the elemental composition of PM2.5 was studied in two scenarios, namely in sugar-cane harvesting (HV) and in non-harvesting (NHV) seasons. The sampling strategy included one campaign in each season. PM2.5 was collected using a dichotomous sampler (10 L·min-1, 24 h) with PTFE filters. Information concerning the bulk elemental concentration was provided by energy-dispersive X-ray fluorescence. Enrichment factor analysis indicated that S, Cl, K, Cr, Ni, Cu, Zn, As, Cd and Pb were highly enriched relative to their crustal ratios (to Al). Principal component analysis was used to get some insight about the sources of the elements. Principal component 1 (PC1) explained 30.5% of data variance. The elements that had high loading (>0.7) were: S, Cr, As, and Pb; these are associated with combustion of fossil fuels. In principal component 2 (PC2), Cl, Cu, Zn, and Cd showed high loadings; these elements are associated with biomass burning. The Ni concentration found is three times larger than the threshold of risk for lung cancer, as recommended by the World Health Organization.
Keywords: A2 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.4236/JEP.2015.65041
|
“Kinetic properties and heme pocket structure of two domains of the polymeric hemoglobin of Artemia in comparison with the native molecule”. Borhani AH, Berghmans H, Trashin S, De Wael K, Fago A, Moens L, Habibi-Rezaei M, Dewilde S, Biochimica et biophysica acta : proteins and proteomics 1854, 1307 (2015). http://doi.org/10.1016/J.BBAPAP.2015.05.007
Abstract: In this project, we studied some physicochemical properties of two different globin domains of the polymeric hemoglobin of the brine shrimp Artemia salina and compared them with those of the native molecule. Two domains (AsHbC1D1 and AsHbC1D5) were cloned and expressed in BL21(DE3)pLysS strain of Escherichiacoli. The recombinant proteins as well as the native hemoglobin (AfHb) were purified from bacteria and frozen Artemia, respectively by standard chromatographic methods and assessed by SDS-PAGE. The heme environment of these proteins was studied by optical spectroscopy and ligand-binding kinetics (e.g. CO association and O2 binding affinity) were measured for the two recombinant proteins and the native hemoglobin. This indicates that the CO association rate for AsHbC1D1 is higher than that of AsHbC1D5 and AfHb, while the calculated P50 value for AsHbC1D1 is lower than that of AsHbC1D5 and AfHb. The geminate and bimolecular rebinding parameters indicate a significant difference between both domains. Moreover, EPR results showed that the heme pocket in AfHb is in a more closed conformation than the heme pocket in myoglobin. Finally, the reduction potential of − 0.13 V versus the standard hydrogen electrode was determined for AfHb by direct electrochemical measurements. It is about 0.06 V higher than the potential of the single domain AsHbC1D5. This work shows that each domain in the hemoglobin of Artemia has different characteristics of ligand binding.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 2.773
DOI: 10.1016/J.BBAPAP.2015.05.007
|
“Neutron activation autoradiography and scanning macro-XRF of Rembrandt van Rijn's Susanna and the Elders (Gemaldegalerie Berlin) : a comparison of two methods for imaging of historical paintings with elemental contrast”. Alfeld M, Laurenze-Landsberg C, Denker A, Janssens K, Noble P, Applied physics A : materials science &, processing 119, 795 (2015). http://doi.org/10.1007/S00339-015-9081-8
Abstract: Imaging methods with elemental contrast are of great value for the investigation of historical paintings, as they allow for study of sub-surface layers that provide insight into a painting's creation process. Two of the most important methods are neutron activation autoradiography (NAAR) and scanning macro-XRF (MA-XRF). Given the differences between these methods in the fundamental physical phenomena exploited, a theoretical comparison of their capabilities is difficult and until now a critical comparison of their use on the same painting is missing. In this paper, we present a study of Rembrandt van Rijn's painting Susanna and the Elders from the Gemaldegalerie in Berlin employing both techniques. The painting features a considerable number of overpainted features and a wide range of pigments with different elemental tracers, including earth pigments (Mn/Fe), Azurite (Cu), lead white (Pb), vermilion (Hg) and smalt (Co, As). MA-XRF can detect all elements above Si (Z = 14), suffers from few spectral overlaps and can be performed in a few tens of hours in situ, i.e. in a museum. NAAR requires the stay of the painting at a research facility for several weeks, and inter-element interferences can be difficult to resolve. Also, only a limited number of elements contribute to the acquired autoradiographs, most notably Mn, Cu, As, Co, Hg and P. However, NAAR provides a higher lateral resolution and is less hindered by absorption in covering layers, which makes it the only method capable of visualizing P in lower paint layers.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 1.455
Times cited: 11
DOI: 10.1007/S00339-015-9081-8
|