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“Increased erythrocyte glutathione peroxidase activity in psoriatics consuming high-selenium drinking water at the dead-sea psoriasis treatment center”. Shani J, Livshitz T, Robberecht H, Van Grieken R, Rubinstein N, Even-Paz Z, Pharmacological research communications 17, 479 (1985). http://doi.org/10.1016/0031-6989(85)90083-9
Abstract: Erythrocyte selenium-dependent glutathione peroxidase activity was measured in psoriatic Danes, before and after their four-week balneological therapy at the Ein-Bokek International Psoriasis Treatment Center, on the Dead-Sea shore in Israel. The drinking water in Ein-Bokek was found to be rich in selenium, a trace element with anticarcinogenic properties and of great importance in human nutrition and health. The most reliable biological parameter for increase in selenium bioavailability is the erythrocytes' glutathione-peroxidase activity. As psoriasis is a proliferative skin disease, the activity of this enzyme was assayed in 35 psoriatic Danes and in 25 long-term local hotel workers, as well as in 34 volunteers drinking low-selenium water. The glutathione peroxidase activity in the psoriatic patients increased significantly during their four-week stay in Ein-Bokek. Erythrocyte glutathione peroxidase activity in the hotel workers was 50% higher than that in the healthy volunteers consuming low-selenium water. A possible role of selenium in psoriasis is suggested.
Keywords: A3 Journal article; Pharmacology. Therapy; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/0031-6989(85)90083-9
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“All crystal clear : 18th-century glass à, la façon de Bohème from the cistercian nunnery of Clairefontaine, Belgium”. Herremans D, Cagno S, Vincke A, Janssens K, De Clercq W, Journal of glass studies 55, 137 (2013)
Abstract: Excavations at the Cistercian nunnery of Clairefontaine, located near Arlon in the south of Belgium, revealed an assemblage of 18th-century colorless glass. The morphology of the vessels and the engraved decoration suggest a central European origin or, at least, stylistic inspiration. The composition of the glass points to a recipe combining silica, lime, and potash: a colorless potash glass a la facon de Boheme. This article considers the technology, morphology, and origin of the vessels. The art-historical analysis is supported by chemical research (scanning electron microscopy energy-dispersive X-ray spectroscopy [SEM-EDX]). The finds are also discussed in light of the emerging northwestern European glass industry, changing consumer practices during the 18th century, and their meaning for the inhabitants of the abbey.
Keywords: A1 Journal article; Art; History; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
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“Influence of sample thickness, excitation energy and geometry on particle size effects in XRF”. Van Dyck P, Markowicz A, Van Grieken R, X-ray spectrometry 14, 183 (1985). http://doi.org/10.1002/XRS.1300140409
Abstract: Expressions are presented for calculating the matrix effect and the pure particle size effect in the XRF analysis of particulate samples with a discrete particle size. The equations are based on the absorption-weighted radiometric diameter concept. Two excitationdetection geometries are considered, with the angles between the sample plane and both the incident and emerging radiation being either 90° (π geometry) or 45° (π/2 geometry). Calculations were made for different sample loadings and exciting radiation energies. The influence of these parameters on the matrix and pure particle size effects is shown. From the results, it is possible to predict the performances of alternative experimental correction procedures for the particle size effect, involving dual measurements at different excitation energies or in different excitationdetection geometries.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1002/XRS.1300140409
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“Elemental constituents of atmospheric aerosols in Recife, North-East Brazil”. Van Grieken R, Van 't dack L, Costa Dantas C, Moura de Amorim W, Maenhaut W, Environmental pollution: series B : chemical and physical 4, 143 (1982). http://doi.org/10.1016/0143-148X(82)90025-8
Abstract: Few data are available on the inorganic atmospheric pollution in the rapidly expanding cities of South America, like Recife, on the Atlantic Coast of North-east Brazil. Therefore, the elemental composition of atmospheric aerosols was investigated for nine sites in the Recife conurbation and a fairly remote site in the area. Total aerosol samples were collected on cellulose filters for analysis by energy dispersive X-ray fluorescence and cascade impactors were used to collect the aerosols as a function of particle size for subsequent analysis by proton-induced X-ray emission. Local soil aliquots were also analysed. About eighteen elements were quantified in all cases. The average total atmospheric concentrations appeared to be well above natural levels but usually lower than, or comparable with, those of North American and European cities. Dispersal of sea spray and of local soil (often contaminated with, for example, Cu, Zn and Pb from industrial sources) contributes predominantly to the total atmospheric load in Recife. However, the particle size fraction results also indicated strong excesses in the small particle mode for S, K, V, Mn, Ni, Cu, Zn, Br and Pb, mainly in the downtown area. Again, the corresponding enrichment factors were only moderate in comparison with other published urban data.
Keywords: A3 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/0143-148X(82)90025-8
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“PCR amplified DNAzyme-amplicons for generic solid-phase antimicrobial resistance screening”. Peeters B, Safdar S, Carlier B, Spasic D, Daems D, Lammertyn J, , 971 (2019)
Abstract: Fiber optic surface plasmon resonance (FO-SPR) has shown its potential for the detection of nucleic acids and more recently the technology has been combined with catalytic active strands such as DNAzymes. In this work, an innovative, generic solid-phase DNA sensor concept is presented, based on FO-SPR and PCR amplified DNAzyme activity. Improved levels of specificity and sensitivity were obtained down to picomolar concentrations. Moreover, the FO-SPR sensor concept enables AuNP amplified DNA target detection, independent of the target sequence length. The FO-SPR sensor was demonstrated for the screening of the mobile colistin resistance (MCR-2) gene, a gene important for the antimicrobial resistance in Gram-negative species such as E. Coli.
Keywords: P1 Proceeding; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
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“Confocal μ-XRF depth analysis of paint layers”. Šmit Ž, Janssens K, Proost K, Langus I, Nuclear instruments and methods in physics research: B: beam interactions with materials and atoms 219, 35 (2004). http://doi.org/10.1016/J.NIMB.2004.01.024
Abstract: Focused narrow-band beam of the synchrotron radiation was used for in-depth analysis of historic and modern paint layers. The fluorescent radiation induced by 21 keV impact radiation was detected by a Si(Li) detector equipped with a polycapillary X-ray lens in con-focal geometry. Scanning of the sample was performed by a motorized xyz stage. Space resolution of 30 ìm was achieved. The procedure of evaluation of concentrations was based on the independent parameter method and included absorption of radiation in the outer layers and secondary fluorescence enhancement induced by hard X-rays of the same and neighboring layers.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 1.109
Times cited: 69
DOI: 10.1016/J.NIMB.2004.01.024
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“Folding of aerosol loaded filters during X-ray fluorescence analysis”. Van Grieken RE, Adams FC, X-ray spectrometry 5, 61 (1976). http://doi.org/10.1002/XRS.1300050204
Abstract: Folding aerosol loaded filters in two with the loaded side inwards during the X-ray analysis not only reduces possible filter heterogeneity effects and improves sample protection, but also increases the sensitivity and renders filter paper absorption corrections simple and more accurate in many instances. It is shown that folding an aerosol loaded Whatman filter paper during Kα X-rays counting leads to an increased sensitivity for all elements up from calcium, scandium or titanium (depending on the sensitivity definition and on the aerosol load) and for all elements up from phosphorus, sulphur or chlorine in the case of the Nuclepore filter. Although the absorption by the filter, into which the aerosol penetrates to some extent, is always more important in the sandwich than in the usual geometry, the dependence of the absorption correction on the usually unknown average deposition depth is less pronounced. Assuming all the aerosol material to be collected at the very surface of the filter and hence being present in the centre of the sandwich to be analysed, leads to an extremely simple filter paper absorption correction which is less prone to uncertainties than more sophisticated corrections in the usual geometry requiring additional measurements. This is the case for all elements up from potassium on Whatman filters and up from phosphorus on Nuclepore filters.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1002/XRS.1300050204
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“Multi-element analysis of urine by energy-dispersive x-ray fluorescence spectrometry”. Vos L, Robberecht H, Van Dyck P, Van Grieken R, Analytica chimica acta 130, 167 (1981). http://doi.org/10.1016/S0003-2670(01)84161-1
Abstract: For multi-element analysis of human urine, 25-ml samples doped with yttrium as internal standard are evaporated gently and then ashed up to 460°C overnight. The residue is pelletized and analysed by energy-dispersive x-ray fluorescence. Acid addition to facilitate the digestion is not mandatory. Recoveries are nearly quantitative for traces of Fe, Ni, Cu, Zn and Sr, to a lesser extent for lead, but not for arsenic or selenium. The standard deviation per measurement is typically around 6%. The detection limits are such that some 10 elements can be determined simultaneously in normal urine, and possibly more in cases of importance to toxicology or industrial hygiene.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/S0003-2670(01)84161-1
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“Single-run ion chromatographic separation of inorganic and low-molecular-mass organic anions under isocratic elution: application to environmental samples”. Krata A, Kontozova-Deutsch V, Bencs L, Deutsch F, Van Grieken R, Talanta : the international journal of pure and applied analytical chemistry 79, 16 (2009). http://doi.org/10.1016/J.TALANTA.2009.02.044
Abstract: For the isocratic ion chromatography (IC) separation of low-molecular-mass organic acids and inorganic anions three different anion-exchange columns were studied: IonPac AS14 (9 ìm particle size), Allsep A-2 (7 ìm particle size), and IC SI-50 4E (5 ìm particle size). A complete baseline separation for all analyzed anions (i.e., F−, acetate, formate, Cl−, NO2−, Br−, NO3−, HPO42− and SO42−) in one analytical cycle of shorter than 17 min was achieved on the IC SI-50 4E column, using an eluent mixture of 3.2 mM Na2CO3 and 1.0 mM NaHCO3 with a flow rate of 1.0 mL min−1. On the IonPac AS14 column, it was possible to separate acetate from inorganic anions in one run (i.e., less than 9 min), but not formate, under the following conditions: 3.5 mM Na2CO3 plus 1.0 mM NaHCO3 with a flow rate of 1.2 mL min−1. Therefore, it was necessary to adapt a second run with a 2.0 mM Na2B4O7 solution as an eluent under a flow rate of 0.8 mL min−1 for the separation of organic ions, which considerably enlarged the analysis time. For the Allsep A-2 column, using an eluent mixture of 1.2 mM Na2CO3 plus 1.5 mM NaHCO3 with a flow rate of 1.6 mL min−1, it was possible to separate almost all anions in one run within 25 min, except the fluoride-acetate critical pair. A Certified Multianion Standard Solution PRIMUS for IC was used for the validation of the analytical methods. The lowest RSDs (less than 1%) and the best LODs (0.02, 0.2, 0.16, 0.11, 0.06, 0.05, 0.04, 0.14 and 0.09 mg L−1 for F−, Ac−, For−, Cl−, NO2−, Br−, NO3−, HPO42− and SO42−, respectively) were achieved using the IC SI-50 4E column. This column was applied for the separation of concerned ions in environmental precipitation samples such as snow, hail and rainwater.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/J.TALANTA.2009.02.044
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“μ-XRF/μ-RS vs. SR μ-XRD for pigment identification in illuminated manuscripts”. van der Snickt G, de Nolf W, Vekemans B, Janssens K, Applied physics A : materials science &, processing 92, 59 (2008). http://doi.org/10.1007/S00339-008-4447-9
Abstract: For the non-destructive identification of pigments and colorants in works of art, in archaeological and in forensic materials, a wide range of analytical techniques can be used. Bearing in mind that every method holds particular limitations, two complementary spectroscopic techniques, namely confocal ì-Raman spectroscopy (ì-RS) and ì-X-ray fluorescence spectroscopy (ì-XRF), were joined in one instrument. The combined ì-XRF and ì-RS device, called PRAXIS unites both complementary techniques in one mobile setup, which allows ì- and in situ analysis. ì-XRF allows one to collect elemental and spatially-resolved information in a non-destructive way on major and minor constituents of a variety of materials. However, the main disadvantages of ì-XRF are the penetration depth of the X-rays and the fact that only elements and not specific molecular combinations of elements can be detected. As a result ì-XRF is often not specific enough to identify the pigments within complex mixtures. Confocal Raman microscopy (ì-RS) can offer a surplus as molecular information can be obtained from single pigment grains. However, in some cases the presence of a strong fluorescence background limits the applicability. In this paper, the concrete analytical possibilities of the combined PRAXIS device are evaluated by comparing the results on an illuminated sheet of parchment with the analytical information supplied by synchrotron radiation ì-X-ray diffraction (SR ì-XRD), a highly specific technique.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 1.455
Times cited: 56
DOI: 10.1007/S00339-008-4447-9
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“Water analysis by spark-source mass-spectrometry after preconcentration on activated carbon”. Vanderborght BM, Van Grieken RE, Talanta : the international journal of pure and applied analytical chemistry 27, 417 (1980). http://doi.org/10.1016/0039-9140(80)80225-6
Abstract: For trace analyses of environmental waters, spark-source mass-spectrometry has been combined with a preconcentration procedure involving chelation of the dissolved trace elements with oxine and subsequent adsorption of the oxinates and naturally occurring organic and colloidal metal species onto activated carbon. The activated carbon is filtered off and ashed at low temperature. The residue is dissolved, an internal standard and pure graphite are added and, after drying, the electrodes are prepared. The photographically recorded mass spectrum is evaluated by a suitable computer routine. The error of the procedure is around 30%. While this preconcentration and analysis procedure is capable of measuring about 40 elements quantitatively, in practice 1025 trace elements are determined simultaneously above the 0.1-μg/l. detection limit, as is illustrated by analyses of drinking water, surface and ground water samples. Although a sophisticated technique, SSMS can be considered for regular panoramic survey analyses.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/0039-9140(80)80225-6
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“Electrochemical detection of MDMA and 2C-B in ecstasy tablets using a selectivity enhancement strategy by in-situ derivatization”. Van Echelpoel R, Kranenburg R, van Asten A, De Wael K, Forensic chemistry 27, 100383 (2022). http://doi.org/10.1016/J.FORC.2021.100383
Abstract: Forensic drug laboratories are confronted with increasing amounts of drugs and a demand for faster results that are directly available on-site. In addition, the drug market is getting more complex with hundreds of new psychoactive substances (NPS) entering the market in recent years. Rapid and on-scene presumptive drug testing therefore faces a shift from manual colorimetric tests towards approaches that can detect a wider range of components and process results automatically. Electrochemical detection offers these desired characteristics, making it a suitable candidate for on-site drug detection. In this study, a two-step electrochemical sensor is introduced for the detection of MDMA and 2C-B. Firstly, a direct electrochemical analysis was performed to detect MDMA. Validation experiments on over 70 substances revealed that 2C-B was the only frequently encountered drug that gave a false positive result for MDMA in this first analysis. A second step using in-situ derivatization was subsequently introduced. To this end, formaldehyde was used for N-methylation of 2C-B thereby enhancing its electrochemical profile. The enriched electrochemical fingerprint in the second step allowed for clear differentiation between MDMA and 2C-B. The applicability of this approach was demonstrated with 71 ecstasy tablets seized by the Amsterdam Police. The MDMA/2C-B sensor correctly identified all 39 MDMA-containing tablets and 10 out of 11 tablets containing 2C-B. Most notably, correct results were also obtained for dark colored tablets in which both spectroscopic analysis and colorimetric tests failed due to obscured signals.
Keywords: A1 Journal article; Pharmacology. Therapy; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab)
Impact Factor: 2.7
DOI: 10.1016/J.FORC.2021.100383
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“Alteration of fossil-bearing shale (Autun, France, Permian), part II : monitoring artificial and natural ageing by combined use of S and Ca K-edge XANES analysis, Rock-Eval pyrolysis and FTIR analysis”. Odin GP, Vanmeert F, Farges F, Gand G, Janssens K, Romero-Sarmiento M-F, Steyer JS, Vantelon D, Rouchon V, Annales de paléontologie 101, 225 (2015). http://doi.org/10.1016/J.ANNPAL.2015.03.001
Abstract: Fossil-bearing shale specimens that include sulfides in their compositions are chemically reactive and sometimes also mechanically fragile. This decay is often related to iron sulfate efflorescence resulting from the oxidation of sulfide compounds. The processes underlying these degradations are poorly known, thus impeding the elaboration of curative or preventive treatments. The present contribution aims to identify the origin of museum specimen alterations. It focuses on the Flouest collection housed at the Museum National d'Histoire Naturelle (MNHN, Paris, France) and originating from the Autun Basin (Saone-et-Loire, France, Permian). To evaluate the alteration of MNHN specimens, it appeared necessary to compare their composition with that of unaltered shale so as to identify chemical changes occurring during ageing. Therefore, new material was collected in the Autun Basin, among others on the locality of Muse that corresponds to the same lithostratigraphic unit as that of the MNHN specimens. This material was, if necessary, artificially aged. The first part of this work, presented elsewhere, deals with the use of Xray diffraction and Mossbauer spectroscopy for characterizing iron reactivity and speciation. It leads to the conclusion that the reactivity of iron in the shale matrix was limited and could not account for the large efflorescence of iron (II) sulfate occurring nearby the fossil. The second part presented here focuses on the use of S K-edge X-ray Absorption Near Edge Structure (XANES) spectroscopy for characterizing sulfur speciation and reactivity. Measurements were performed on the shale matrix and on thin layers of maceral found in the proximity of damaged areas. As sulfur may be found in association with calcium or organic matter, complementary techniques were implemented, such as FTIR spectroscopy, Rock-Eval pyrolysis (characterization of organic matter content) and Ca K-edge XANES (analysis of calcium speciation) spectroscopy. It was shown that sulfur is mainly related to thioether, sulfoxide, iron sulfide, and sulfates whereas calcium is mainly bound to carboxylate, carbonate and/or sulfate groups. FTIR analysis of the macerals confirmed the presence of vitrinite on damaged MNHN specimens. The low oxygen content of new shale samples determined by Rock-Eval pyrolysis indicates that the organic matter is well preserved, despite the fact that samples come from outcrop surface. In the newly collected material, sulfur is mainly related to organic sulfides (thioether) with a minor occurrence of iron sulfide. In the shale fraction of damaged MNHN specimens, sulfur is mostly oxidized into a mixture of iron and calcium sulfate. However, in the vitrinite layers of the same specimens, a large proportion of sulfur corresponds to organic sulfides. Also the oxidation of sulfur does not occur homogeneously but preferentially in the shale fraction, probably because this latter is porous whereas vitrinite is not. Artificial ageing of new shale material showed that the oxidation of organic sulfides could be reproduced at 90 degrees C, 80% of relative humidity. However, the obtained efflorescence almost exclusively corresponds to calcium sulfate whereas iron (II) sulfates are mostly observed on MNHN specimens. The new material collected on site is probably to be questioned, and future studies will have to select new samples with fossil remains. This will be the object of the third part of this work. (C) 2015 Elsevier Masson SAS. All rights reserved.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 1.113
Times cited: 6
DOI: 10.1016/J.ANNPAL.2015.03.001
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“Removal of natural organic matter from water by using ion-exchange resins”. Kabsch-Korbutowicz M, Krupinska B, Przemysl chemiczny
T2 –, Scientific and Technical Conference on Water and Wastewater Basis for, Environmental Protection (School of Quality Water 2008), MAY 28-30, 2008, Kolobrzeg, POLAND 87, 473 (2008)
Abstract: Four aq. solns. contg. natural peat components and the water from Odra river were treated with 3 anion-exchange resins (2.5 to 15 cm(3) of resin per 1 dm(3) of the sample) for 5-60 min to remove the org. matter. The process efficiency was detd. by UV absorbance (254 nm) and colour intensity measurements. The treatment resulted in discoloration of the solns. A resin with weak alky, was the most efficient. The degree of removal increased with increasing the resin dose and contact time. The presence of inorg. anions in the soins. contributed to a decrease of process effectivity.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
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“Preparation of conducting electrodes from biological samples for multi-element trace analysis by spark-source mass spectrometry or emission spectrometry”. Vos L, Van Grieken R, Analytica chimica acta 164, 83 (1984). http://doi.org/10.1016/S0003-2670(00)85619-6
Abstract: Four decomposition procedures frequently used for biological material (dry ashing, open wet digestion, wet digestion in a teflon bomb and low-temperature ashing) are optimized for the conversion of biological samples to conducting electrodes suitable for multi-element trace determinations by spark-source mass spectrometry or emission spectrometry. The optimized procedures are evaluated with respect to contamination, retention and preconcentration of the trace elements, homogeneity of the electrodes and precision of the final results. Both dry-ashing methods are prone to losses by volatilization; simple dry ashing suffers from contamination problems during electrode preparation. Wet digestion gives better precision; digestion with nitric/sulfuric acids in an open flask is the method of choice for most elements being simpler and giving lower blanks than the bomb method.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/S0003-2670(00)85619-6
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“Comparison of x-ray absorption and emission techniques for the investigation of paintings”. Cabal A, Schalm O, Eyskens P, Willems P, Harth A, van Espen P, X-ray spectrometry 44, 141 (2015). http://doi.org/10.1002/XRS.2591
Abstract: Four x-ray techniques: computed radiography, emission radiography, energy-resolved radiography and imaging x-ray fluorescence were compared using four mock-up panel paintings. The paintings have different stratigraphy and pigments and are representative for different historical periods. One of the paintings has a hidden underlying painting. The type of pigments used mainly influences the information obtained by both the emission and absorption measurements; high-Z white pigment and high-Z color pigments giving the best contrast. Each of the techniques revealed interesting aspects of the paintings, but none of them could reveal the hidden painting to a satisfactory level. Due to the statistical quality of the spectral data, x-ray fluorescence gives elemental images with high contrast. The radiographic images are better to reveal the internal structure. Imaging x-ray fluorescence and energy-resolved radiography measurements can be done simultaneously, and the combination has the highest potential for the study of complex multilayer paintings. Copyright (c) 2015 John Wiley & Sons, Ltd.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Cultural Heritage Sciences (ARCHES)
DOI: 10.1002/XRS.2591
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“Selectivity in ligand functionalization of photocatalytic metal oxide nanoparticles for phase transfer and self‐assembly applications”. Borah R, Ninakanti R, Nuyts G, Peeters H, Pedrazo-Tardajos A, Nuti S, Vande Velde C, De Wael K, Lenaerts S, Bals S, Verbruggen S, Chemistry-A European Journal , chem.202100029 (2021). http://doi.org/10.1002/CHEM.202100029
Abstract: Functionalization of photocatalytic metal oxide nanoparticles of TiO 2 , ZnO, WO 3 and CuO with amine‐terminated (oleylamine) and thiol‐terminated (1‐dodecanethiol) alkyl chained ligands was studied under ambient conditions. A high selectivity was observed in the binding specificity of a ligand towards nanoparticles of these different oxides. It was observed that oleylamine binds stably to only TiO 2 and WO 3 , while 1‐dodecanethiol binds stably only to ZnO and CuO. Similarly, polar to non‐polar solvent phase transfer of TiO 2 and WO 3 nanoparticles could be achieved by using oleylamine, but not by 1‐dodecanethiol, while the contrary holds for ZnO and CuO. The surface chemistry of ligand functionalized nanoparticles was probed by ATR‐FTIR spectroscopy, that enabled to elucidate the occupation of the ligands at the active sites. The photo‐stability of the ligands on the nanoparticle surface was determined by the photocatalytic self‐cleaning properties of the material. While TiO 2 and WO 3 degrade the ligands within 24 hours under both UV and visible light, ligands on ZnO and CuO remain unaffected. The gathered insights are also highly relevant from an application point of view. As an example, since the ligand functionalized nanoparticles are hydrophobic in nature, they can thus be self‐assembled at the air‐water interface, for obtaining nanoparticle films with demonstrated photocatalytic as well as anti‐fogging properties.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Sustainable Energy, Air and Water Technology (DuEL); Intelligence in PRocesses, Advanced Catalysts and Solvents (iPRACS)
Impact Factor: 5.317
Times cited: 15
DOI: 10.1002/CHEM.202100029
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“Degradation of galvanised iron roofing material in Tanzania by atmospheric corrosion”. Potgieter-Vermaak SS, Mmari A, Van Grieken R, McCrindle RI, Potgieter JH, Corrosion engineering science and technology 46, 642 (2011). http://doi.org/10.1179/147842210X12695149033972
Abstract: Galvanised iron is popular in many applications, particular as a roofing material. However, just like other materials, especially metallic ones, it is prone to degradation by corrosion. In this particular study, the degradation of galvanised roof sheets was investigated at a coastal, urban and rural site in Tanzania, Africa. Samples were exposed to various outdoor environments over a period of 3 years. In addition, some accelerated laboratory investigations were conducted in different simulated air pollution environments in an artificial corrosion chamber constructed for this purpose to supplement the outdoor exposure tests. It was found that the combination of the tropical climate and increasing air pollution due to industrial development in the capital Dar-es-Salaam resulted in substantial atmospheric corrosion of the roof sheets, which eventually leads to failure and the necessity for replacement. The rural site had the lowest degree of atmospheric corrosion as expected. A combination of different corrosion products was identified as a result of the atmospheric corrosion by Raman and EDX analyses. The information gained from this investigation could be utilised to construct more durable structures requiring less frequent replacement and maintenance in future.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1179/147842210X12695149033972
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“Nanoscale investigation of the degradation mechanism of a historical chrome yellow paint by quantitative electron energy loss spectroscopy mapping of chromium species”. Tan H, Tian H, Verbeeck J, Janssens K, Van Tendeloo G, Angewandte Chemie: international edition in English 52, 11360 (2013). http://doi.org/10.1002/anie.201305753
Abstract: Getting the picture: The investigation of 100 year old chrome yellow paint by transmission electron microscopy and spectroscopy has led to the identification of four types of coreshell particles. This nanoscale investigation has allowed a mechanism to be proposed for the darkening of some bright yellow colors in Van Gogh's paintings (e.g. in Falling leaves (Les Alyscamps), 1888).
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 11.994
Times cited: 29
DOI: 10.1002/anie.201305753
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“The colour of silver stained glass : analytical investigations carried out with XRF, SEM/EDX, TEM and IBA”. Jembrih-Simbürger D, Neelmeijer C, Schalm O, Fredrickx P, Schreiner M, De Vis K, Mäder M, Schryvers D, Caen J, Journal of analytical atomic spectrometry 17, 321 (2002). http://doi.org/10.1039/b111024c
Abstract: Glass treated on its surface with silver compounds and an aluminosilicate, such as ochre or clay, at higher temperatures (between 550 and 650 °C) accepts a wide variety of a yellow colour. It is the aim of this study to investigate the parameters of the manufacturing process affecting the final colour of silver stained glass and to correlate them with the final colour and colour intensity. Therefore, defined mixtures of ochre and a silver compound (AgCl, AgNO3, Ag2SO4, Ag3PO4, Ag2O) were prepared and applied on soda-lime glass. The firing process was modified within the range from 563 to 630 °C and glass samples were analysed after treatment with energy dispersive X-ray fluorescence analysis (EDXRF), scanning electron microscopy (SEM/EDX), transmission electron microscopy (TEM), as well as ion beam analysis (IBA) with an external beam. Within the scope of IBA simultaneous measurements using particle-induced X-ray emission (PIXE), particle-induced gamma-ray emission (PIGE), and Rutherford backscattering spectrometry (RBS) were carried out in order to obtain the thickness of the Ag-rich surface layer and the depth distribution of Ag. By means of TEM the microstructure of the silver particles was visualised. XRF results show that the lowest amount of Ag could be detected on glass samples treated with silver stain mixtures containing AgCl and Ag2O. A low kiln temperature (e.g. 563 °C) results in a higher silver concentration at the surface and lower penetration depths. Furthermore, the results obtained with SEM/EDX at cross-sections of the glass samples could be confirmed by PIXE, PIGE, RBS, and TEM.
Keywords: A1 Journal article; Art; Electron microscopy for materials research (EMAT); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 3.379
Times cited: 42
DOI: 10.1039/b111024c
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“An N-myristoylated globin with a redox-sensing function that regulates the defecation cycle in Caenorhabditis elegans”. Tilleman L, De Henau S, Pauwels M, Nagy N, Pintelon I, Braeckman BP, De Wael K, Van Doorslaer S, Adriaensen D, Timmermans J-P, Moens L, Dewilde S, PLoS ONE 7, e48768 (2012). http://doi.org/10.1371/JOURNAL.PONE.0048768
Abstract: Globins occur in all kingdoms of life where they fulfill a wide variety of functions. In the past they used to be primarily characterized as oxygen transport/storage proteins, but since the discovery of new members of the globin family like neuroglobin and cytoglobin, more diverse and complex functions have been assigned to this heterogeneous family. Here we propose a function for a membrane-bound globin of C. elegans, GLB-26. This globin was predicted to be myristoylated at its N-terminus, a post-translational modification only recently described in the globin family. In vivo, this globin is found in the membrane of the head mesodermal cell and in the tail stomato-intestinal and anal depressor muscle cells. Since GLB-26 is almost directly oxidized when exposed to oxygen, we postulate a possible function as electron transfer protein. Phenotypical studies show that GLB-26 takes part in regulating the length of the defecation cycle in C. elegans under oxidative stress conditions.
Keywords: A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 2.806
Times cited: 6
DOI: 10.1371/JOURNAL.PONE.0048768
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“Gold-sputtered microelectrodes with built-in gold reference and counter electrodes for electrochemical DNA detection”. Thiruvottriyur Shanmugam S, Trashin S, De Wael K, Analyst (2020). http://doi.org/10.1039/D0AN01387K
Abstract: Gold-sputtered microelectrodes with built-in gold reference and counter electrodes represent a promising platform for the development of disposable DNA sensors. Pretreating gold electrode surfaces and immobilization of DNA thereon is commonly employed in biosensing applications. However, with no scientific or practical guidelines to prepare a DNA sensor using these miniature gold-sputtered microelectrodes, cleaning and immobilization steps need to be systematically optimized and updated. In this work, we present efficient cleaning and modification of miniaturized gold-sputtered microelectrodes with thiolated DNA probes for DNA detection. Additional discussions on subtleties and nuances involved at each stage of pretreating and modifying gold-sputtered microelectrodes are included to present a robust, well-founded protocol. It was evident that the insights on cleaning polycrystalline gold disk electrodes with a benchmark electrode surface for DNA sensors, cannot be transferred to clean these miniature gold-sputtered microelectrodes. Therefore, a comparison between five different cleaning protocols was made to find the optimal one for gold-sputtered microelectrodes. Additionally, two principally different immobilization techniques for gold-sputtered microelectrode modification with thiolated ssDNA were compared i.e., immobilization through passive chemisorption and potential perturbation were compared in terms of thiol-specific attachment and thiol-unspecific adsorption through nitrogenous bases. The hybridization performance of these prepared electrodes was characterized by their sensitive complementary DNA capturing ability, detected by a standard alkaline phosphatase assay. Immobilization through passive chemisorption proved to be efficient in capturing the complementary target DNA with a detection limit of 0.14 nM and sensitivity of 9.38 A M−1 cm2. In general, this work presents a comprehensive understanding of cleaning, modification and performance of gold-sputtered microelectrodes with built-in gold reference and counter electrodes for both fundamental investigations and practical DNA sensing applications.
Keywords: A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 4.2
DOI: 10.1039/D0AN01387K
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“A graphene oxide amplification platform tagged with tyrosinase-zinc oxide quantum dot hybrids for the electrochemical sensing of hydroxylated polychlorobiphenyls”. Rather JA, Pilehvar S, De Wael K, Sensors and actuators : B : chemical 190, 612 (2014). http://doi.org/10.1016/J.SNB.2013.09.018
Abstract: Graphene oxide can act as an amplification platform for the immobilization of a hybrid structure composed of tyrosinase (Tyr) and zinc oxide quantum dots (ZnO QDs). This article describes how this platform increases the sensitivity for the detection of hydroxylated polychlorobiphenyls (OH-PCBs). The adsorption of Tyr (with low isoelectric point) on the positively charged surface of ZnO QDs is based on electrostatic interactions. The scanning electron microscopic images and UVvis spectroscopic analysis demonstrated the adsorption of Tyr on ZnO QDs. The stepwise assembly process of the fabricated biosensor was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The synthesized ZnO QDs and graphene oxide were characterized by Raman spectroscopy, infrared spectroscopy, X-ray diffraction and scanning electron microscopic techniques. The determination of OH-PCBs was carried out by using square wave voltammetry over the concentration range of 2.827.65 μM with a detection limit of 0.15 μM with good reproducibility, selectivity and acceptable stability. The high value of surface coverage of ZnO QDs and small value of MichaelisMenten constant (View the MathML source) confirmed an excellent loading of the Tyr and a high affinity of the biosensor toward the detection of OH-PCBs. This biosensor and the described sensing platform offer a great potential for rapid, cost-effective and on-field analysis of OH-PCBs.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 5.401
Times cited: 26
DOI: 10.1016/J.SNB.2013.09.018
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“Mineral dust variability in central West Antarctica associated with ozone depletion”. Cataldo, Evangelista H, Simões JC, Godoi RHM, Simmonds I, Hollanda MH, Wainer I, Aquino FE, Van Grieken R, Atmospheric chemistry and physics discussions 12, 12685 (2012). http://doi.org/10.5194/ACPD-12-12685-2012
Abstract: Here we show that mineral dust retrieved from an ice core in the central West Antarctic sector, spanning the last five decades, provides evidence that northerly air mass incursions into Antarctica, tracked by dust microparticles, have slightly declined. This result contrasts with dust in ice core records reported in West/coastal Antarctica, which show significant increases to the present day. We attribute that difference, in part, to changes in the regional climate regime triggered by the ozone depletion and its consequences for the polar vortex intensity. The vortex maintains the Antarctic central region relatively isolated from mid-latitude air mass incursions with implications to the intensification of the Westerlies and to a persistent positive phase of the Southern Annular Mode. We also show that variability of the diameter of insoluble microparticles in central West Antarctica can be modeled by linear/quadratic functions of both cyclone depth (energy) and wind intensity around Antarctica.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.5194/ACPD-12-12685-2012
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“Identifying Electrochemical Fingerprints of Ketamine with Voltammetry and Liquid Chromatography–Mass Spectrometry for Its Detection in Seized Samples”. Schram J, Parrilla M, Sleegers N, Samyn N, Bijvoets SM, Heerschop MWJ, van Nuijs ALN, De Wael K, Analytical Chemistry 92, 13485 (2020). http://doi.org/10.1021/acs.analchem.0c02810
Abstract: Herein, a straightforward electrochemical approach for the determination of ketamine in street samples and seizures is presented by employing screen-printed electrodes (SPE). Square wave voltammetry (SWV) is used to study the electrochemical behavior of the illicit drug, thus profiling the different oxidation states of the substance at different pHs. Besides, the oxidation pathway of ketamine on SPE is investigated for the first time with liquid chromatography–high-resolution mass spectrometry. Under the optimized conditions, the calibration curve of ketamine at buffer solution (pH 12) exhibits a sensitivity of 8.2 μA μM–1, a linear relationship between 50 and 2500 μM with excellent reproducibility (RSD = 2.2%, at 500 μM, n = 7), and a limit of detection (LOD) of 11.7 μM. Subsequently, binary mixtures of ketamine with adulterants and illicit drugs are analyzed with SWV to investigate the electrochemical fingerprint. Moreover, the profile overlapping between different substances is addressed by the introduction of an electrode pretreatment and the integration of a tailor-made script for data treatment. Finally, the approach is tested on street samples from forensic seizures. Overall, this system allows for the on-site identification of ketamine by law enforcement agents in an easy-to-use and rapid manner on cargos and seizures, thereby disrupting the distribution channel and avoiding the illicit drug reaching the end-user.
Keywords: A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Toxicological Centre
Impact Factor: 7.4
DOI: 10.1021/acs.analchem.0c02810
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“The sweet detection of rolling circle amplification : glucose-based electrochemical genosensor for the detection of viral nucleic acid”. Ciftci S, Cánovas R, Neumann F, Paulraj T, Nilsson M, Crespo GA, Madaboosi N, Biosensors &, Bioelectronics 151, 112002 (2020). http://doi.org/10.1016/J.BIOS.2019.112002
Abstract: Herein, an isothermal padlock probe-based assay for the simple and portable detection of pathogens coupled with a glucose oxidase (GOx)-based electrochemical readout is reported. Infectious diseases remain a constant threat on a global scale, as in recurring pandemics. Rapid and portable diagnostics hold the promise to tackle the spreading of diseases and decentralising healthcare to point-of-care needs. Ebola, a hypervariable RNA virus causing fatalities of up to 90% for recent outbreaks in Africa, demands immediate attention for bedside diagnostics. The design of the demonstrated assay consists of a rolling circle amplification (RCA) technique, responsible for the generation of nucleic acid amplicons as RCA products (RCPs). The RCPs are generated on magnetic beads (MB) and subsequently, connected via streptavidin-biotin bonds to GOx. The enzymatic catalysis of glucose by the bound GOx allows for an indirect electrochemical measurement of the DNA target. The RCPs generated on the surface of the MB were confirmed by scanning electron microscopy, and among other experimental conditions such as the type of buffer, temperature, concentration of GOx, sampling and measurement time were evaluated for the optimum electrochemical detection. Accordingly, 125 μg mL−1 of GOx with 5 mM glucose using phosphate buffer saline (PBS), monitored for 1 min were selected as the ideal conditions. Finally, we assessed the analytical performance of the biosensing strategy by using clinical samples of Ebola virus from patients. Overall, this work provides a proof-of-concept bioassay for simple and portable molecular diagnostics of emerging pathogens using electrochemical detection, especially in resource-limited settings.
Keywords: A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 12.6
DOI: 10.1016/J.BIOS.2019.112002
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“Thin-layer potentiometry for creatinine detection in undiluted human urine using ion-exchange membranes as barriers for charged interferences”. Liu Y, Cánovas R, Crespo GA, Cuartero M, Analytical Chemistry 92, 3315 (2020). http://doi.org/10.1021/ACS.ANALCHEM.9B05231
Abstract: Herein, thin-layer potentiometry combined with ion-exchange membranes as barriers for charged interferences is demonstrated for the analytical detection of creatinine (CRE) in undiluted human urine. Briefly, CRE diffuses through an anion-exchange membrane (AEM) from a sample contained in one fluidic compartment to a second reservoir, containing the enzyme CRE deiminase. There, CRE reacts with the enzyme, and the formation of ammonium is dynamically monitored by potentiometric ammonium-selective electrodes. This analytical concept is integrated into a lab-on-a-chip microfluidic cell that allows for a high sample throughput and the operation under stop-flow mode, which allows CRE to passively diffuse across the AEM. Conveniently, positively charged species (i.e., potassium, sodium, and ammonium, among others) are repelled by the AEM and never reach the ammonium-selective electrodes; thus, possible interference in the response can be avoided. As a result, the dynamic potential response of the electrodes is entirely ascribed to the stoichiometric formation of ammonium. The new CRE biosensor exhibits a Nernstian slope, within a linear range of response from 1 to 50 mM CRE concentration. As expected, the response time (15–60 min) primarily depends on the CRE diffusion across the AEM. CRE analysis in urine samples displayed excellent results, without requiring sample pretreatment (before the introduction of the sample in the microfluidic chip) and with high compatibility with development into a potential point-of-care clinical tool. In an attempt to decrease the analysis time, the presented analytical methodology for CRE detection is translated into an all-solid-state platform, in which the enzyme is immobilized on the surface of the ammonium-selective electrode and with the AEM on top. While more work is necessary in this direction, the CRE sensor appears to be promising for CRE analysis in both urine and blood.
Keywords: A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 7.4
DOI: 10.1021/ACS.ANALCHEM.9B05231
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“Climatic quality evaluation by peak analysis and segregation of low-, mid-, and high-frequency fluctuations, applied on a historic chapel”. Anaf W, Schalm O, Building and environment 148, 286 (2019). http://doi.org/10.1016/J.BUILDENV.2018.11.018
Abstract: Heritage-related guidelines and standards recommend stable climatic conditions, since these contribute to the extension of heritage collections life. As a result, numerous museums and other heritage institutions implement (expensive) mitigation measures to achieve stable conditions. Nevertheless, temperature and relative humidity fluctuations are often still observed. This contribution demonstrates that the analysis of temperature and humidity peaks and drops helps to identify hazards which cause fluctuations in different frequency ranges. This hazard identification provides information on the type of mitigation actions that are required in the near future and in which order they need to be implemented. The approach is illustrated with a case study. A 22 month monitoring campaign was performed in a chapel in the center of Antwerp (Belgium) where the climatic conditions are controlled with a heating, ventilation and air conditioning (HVAC) system. Low-, mid- and high-frequency fluctuations were separated and discussed for their hazards.
Keywords: A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Cultural Heritage Sciences (ARCHES)
DOI: 10.1016/J.BUILDENV.2018.11.018
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“Atomic-level understanding for the enhanced generation of hydrogen peroxide by the introduction of an aryl amino group in polymeric carbon nitrides”. Zhang T, Schilling W, Khan SU, Ching HYV, Lu C, Chen J, Jaworski A, Barcaro G, Monti S, De Wael K, Slabon A, Das S, Acs Catalysis 11, 14087 (2021). http://doi.org/10.1021/ACSCATAL.1C03733
Abstract: Heterogeneous catalysts are often & ldquo;black boxes & rdquo; due to the insufficient understanding of the detailed mechanisms at the catalytic sites. An atomic-level elucidation of the processes taking place in those regions is, thus, mandatory to produce robust and selective heterogeneous catalysts. We have improved the description of the whole reactive scenario for polymeric carbon nitrides (PCN) by combining atomic-level characterizations with magic-angle spinning (MAS) solid-state nuclear magnetic resonance (NMR) spectroscopy, classical reactive molecular dynamics (RMD) simulations, and quantum chemistry (QC) calculations. We disclose the structure & minus;property relationships of an ad hoc modified PCN by inserting an aryl amino group that turned out to be very efficient for the production of H2O2. The main advancement of this work is the development of a difluoromethylene-substituted aryl amino PCN to generate H2O2 at a rate of 2.0 mM & middot;h & minus;1 under the irradiation of household blue LEDs and the identification of possible active catalytic sites with the aid of 15N and 19F MAS solid-state NMR without using any expensive labeling reagent. RMD simulations and QC calculations confirm and further extend the experimental descriptions by revealing the role and locations of the identified functionalities, namely, NH linkers, & minus;NH2 terminal groups, and difluoromethylene units, reactants, and products. <comment>Superscript/Subscript Available</comment
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Organic synthesis (ORSY); Applied Electrochemistry & Catalysis (ELCAT); Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab)
Impact Factor: 10.614
DOI: 10.1021/ACSCATAL.1C03733
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“Mobile depth profiling and sub-surface imaging techniques for historical paintings : a review”. Alfeld M, Broekaert JAC, Spectrochimica acta: part B : atomic spectroscopy 88, 211 (2013). http://doi.org/10.1016/J.SAB.2013.07.009
Abstract: Hidden, sub-surface paint layers and features contain valuable information for the art-historical investigation of a painting's past and for its conservation for coming generations. The number of techniques available for the study of these features has been considerably extended in the last decades and established techniques have been refined. This review focuses on mobile non-destructive subsurface imaging and depth profiling techniques, which allow for the in-situ investigation of easel paintings, i.e. paintings on a portable support. Among the techniques discussed are: X-ray radiography and infrared reflectography, which are long established methods and are in use for several decades. Their capabilities of element/species specific imaging have been extended by the introduction of energy/wavelength resolved measurements. Scanning macro-X-ray fluorescence analysis made it for the first time possible to acquire elemental distribution images in-situ and optical coherence tomography allows for the non-destructive study the surface paint layers in virtual cross-sections. These techniques and their variants are presented next to other techniques, such as Terahertz imaging, Nuclear Magnetic Resonance depth profiling and established techniques for non destructive testing (thermography, ultrasonic imaging and laser based interference methods) applied in the conservation of historical paintings. Next to selected case studies the capabilities and limitations of the techniques are discussed. (C) 2013 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/J.SAB.2013.07.009
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