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“Exsolution of SrO during the Topochemical Conversion of LaSr3CoRuO8to the Oxyhydride LaSr3CoRuO4H4”. Jin L, Batuk M, Kirschner FKK, Lang F, Blundell SJ, Hadermann J, Hayward MA, Inorganic chemistry 58, 14863 (2019). http://doi.org/10.1021/acs.inorgchem.9b02552
Abstract: Reaction of the n = 1 Ruddlesden-Popper oxide LaSr3CoRuO8 with CaH2 yields the oxyhydride phase LaSr3CoRuO4H4 via topochemical anion-exchange. Close inspection of X-ray and neutron powder diffraction data in combination with HAADF-STEM images reveals that nanoparticles of SrO are exsolved from the system during the reaction, with the change in cation stoichiometry accommodated by the inclusion of n > 1 (Co/Ru)nOn+1H2n ‘perovskite’ layers into the Ruddlesden-Popper stacking sequence. This novel pseudo-topochemical process offers a new route for the formation of n > 1 Ruddlesden-Popper structured materials. Magnetization data are consistent with a LaSr3Co1+Ru2+O4H4 (Co1+, d8, S = 1; Ru2+, d6, S = 0) oxidation/spin state combination. Neutron diffraction and μ+SR data show no evidence for long-range magnetic order down to 2 K, suggesting the diamagnetic Ru2+ centers impede the Co-Co magnetic exchange interactions.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4.857
Times cited: 1
DOI: 10.1021/acs.inorgchem.9b02552
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“Locating and controlling the Zn content in In(Zn)P quantum dots”. Kirkwood N, De Backer A, Altantzis T, Winckelmans N, Longo A, Antolinez FV, Rabouw FT, De Trizio L, Geuchies JJ, Mulder JT, Renaud N, Bals S, Manna L, Houtepen AJ, Chemistry of materials 32, 557 (2019). http://doi.org/10.1021/acs.chemmater.9b04407
Abstract: Zinc is routinely employed in the synthesis of InP quantum dots (QDs) to improve the photoluminescence efficiency and carrier mobility of the resulting In(Zn)P alloy nanostructures. The exact location of Zn in the final structures and the mechanism by which it enhances the optoelectronic properties of the QDs is debated. We use synchrotron X-ray absorbance spectroscopy to show that the majority of Zn in In(Zn)P QDs is located at their surface as Zn-carboxylates. However, a small amount of Zn is present inside the bulk of the QDs with the consequent contraction of their lattice, as confirmed by combining high resolution high-angle annular dark-field imaging scanning transmission electron microscopy (HAADF-STEM) with statistical parameter estimation theory. We further demonstrate that the Zn content and its incorporation into the QDs can be tuned by the ligation of commonly employed Zn carboxylate precursors: the use of highly reactive Zn-acetate leads to the formation of undesired Zn3P2 and the final nanostructures being characterized by broad optical features, whereas Zn-carboxylates with longer carbon chains lead to InP crystals with much lower zinc content and narrow optical features. These results can explain the differences between structural and optical properties of In(Zn)P samples reported across the literature, and provide a rational method to tune the amount of Zn in InP nanocrystals and to drive the incorporation of Zn either as surface Zn-carboxylate, as a substitutional dopant inside the InP crystal lattice, or even predominantly as Zn3P2.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 39
DOI: 10.1021/acs.chemmater.9b04407
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“Cephalosporin antibiotics : electrochemical fingerprints and core structure reactions investigated by LC-MSMS”. Sleegers N, van Nuijs ALN, van den Berg M, De Wael K, Analytical chemistry 91, 2035 (2019). http://doi.org/10.1021/ACS.ANALCHEM.8B04487
Abstract: Electrochemistry and exploiting electrochemical fingerprints is a potent approach to address newly emerging surveillance needs, for instance for antibiotics. However, a comprehensive insight in the electrochemical oxidation behaviour and mechanism is re-quired for this sensing strategy. To address the lack in knowledge of the voltammetric behaviour of the cephalosporins antibiotics, a selection of cephalosporin antibiotics and two main intermediates were subjected to an electrochemical study of their redox behaviour by means of pulsed voltammetric techniques and small-scale electrolysis combined with HPLC-MS/MS analyses. Sur-prisingly, the detected oxidation products did not fit the earlier suggested oxidation of the sulfur group to the corresponding sul-foxide. The influence of different side chains, both at the three and the seven position of the β-lactam core structure on the elec-trochemical fingerprint were investigated. Additional oxidation signals at lower potentials were elucidated and linked to different side chains. These signals were further exploited to allow simultaneous detection of different cephalosporins in one voltammetric sweep. These fundamental insights can become the building blocks for an new on-site screening method.
Keywords: A1 Journal article; Pharmacology. Therapy; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Toxicological Centre
Impact Factor: 6.32
Times cited: 6
DOI: 10.1021/ACS.ANALCHEM.8B04487
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“Challenges in the electrochemical (bio)sensing of non-electroactive food and environmental contaminants”. Moro G, De Wael K, Moretto LM, Current opinion in electrochemistry 16, 57 (2019). http://doi.org/10.1016/J.COELEC.2019.04.019
Abstract: The electrochemical detection of non-electroactive contaminants can be successfully faced via the use of indirect detection strategies. These strategies can provide sensitive and selective responses often coupled with portable and user-friendly analytical tools. Indirect detection strategies are usually based on the change in the signal of an electroactive probe, induced by the presence of the target molecule at a modified electrode. This critical review aims at addressing the developments in indirect electro-sensing strategies for non-electroactive contaminants in food and environmental analysis in the last years (2017-2019). Emphasis is given to the strategy design, the electrode modifiers used and the feasibility of technological transfer.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Times cited: 4
DOI: 10.1016/J.COELEC.2019.04.019
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“Conductive imprinted polymers for the direct electrochemical detection of beta-lactam antibiotics: The case of cefquinome”. Moro G, Bottari F, Sleegers N, Florea A, Cowen T, Moretto LM, Piletsky S, De Wael K, Sensors and actuators : B : chemical 297, 126786 (2019). http://doi.org/10.1016/J.SNB.2019.126786
Abstract: A biomimetic sensor for cefquinome (CFQ) was designed at multi-walled carbon nanotubes modified graphite screen-printed electrodes (MWCNTs-G-SPEs) as a proof-of-concept for the creation of a sensors array for beta-lactam antibiotics detection in milk. The sensitive and selective detection of antibiotic residues in food and environment is a fundamental step in the elaboration of prevention strategies to fight the insurgence of antimicrobial resistance (AMR) as recommended by authorities around the world (EU, WHO, FDA). The detection strategy is based on the characteristic electrochemical fingerprint of the target antibiotic cefquinome. A conducive electropolymerized molecularly imprinted polymer (MIP) coupled with MWCNTs was found to be the optimal electrode modifier, able to provide an increased selectivity and sensitivity for CFQ detection. The design of CFQ-MIP was facilitated by the rational selection of the monomer, 4-aminobenzoic acid (4-ABA). The electropolymerization process of 4-ABA have not been fully elucidated yet; for this reason a thorough study and optimization of electropolymerization conditions was performed to obtain a conducive and stable poly(4-ABA) film. The modified electrodes were characterized by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and cyclic voltammetry (CV). CFQ-MIP were synthesized at MWCNT-G-SPEs by electropolyrnerization in pH approximate to 1 (0.1 M sulphuric acid) with a monomer:template ratio of 5:1. Two different analytical protocols were tested (single and double step detection) to minimize unspecific adsorptions and improve the sensitivity. Under optimal conditions, the lowest CFQ concentration detectable by square wave voltammetry (SWV) at the modified sensor was 50 nM in 0.1 M phosphate buffer pH 2.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 5.401
Times cited: 4
DOI: 10.1016/J.SNB.2019.126786
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“Electrochemical strategies for adulterated heroin samples”. Florea A, Schram J, De Jong M, Eliaerts J, Van Durme F, Kaur B, Samyn N, De Wael K, Analytical chemistry 91, 7920 (2019). http://doi.org/10.1021/ACS.ANALCHEM.9B01796
Abstract: Electrochemical strategies to selectively detect heroin in street samples without the use of complicated electrode modifications were developed for the first time. For this purpose, heroin, mixing agents (adulterants, cutting agent, and impurities), and their binary mixtures were subjected to square wave voltammetry measurements at bare graphite electrodes at pH 7.0 and pH 12.0, in order to elucidate the unique electrochemical fingerprint of heroin and mixing agents as well as possible interferences or reciprocal influences. Adjusting the pH from pH 7.0 to pH 12.0 allowed a more accurate detection of heroin in the presence of most common mixing agents. Furthermore, the benefit of introducing a preconditioning step prior to running square wave voltammetry on the electrochemical fingerprint enrichment was explored. Mixtures of heroin with other drugs (cocaine, 3,4-methylenedioxymethamphetamine, and morphine) were also tested to explore the possibility of their discrimination and simultaneous detection. The feasibility of the proposed electrochemical strategies was tested on realistic heroin street samples from forensic cases, showing promising results for fast, on-site detection tools of drugs of abuse.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 6.32
Times cited: 2
DOI: 10.1021/ACS.ANALCHEM.9B01796
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“Enzymatic sensor for phenols based on titanium dioxide generating surface confined ROS after treatment with H2O2”. Rahemi V, Trashin S, Hafideddine Z, Meynen V, Van Doorslaer S, De Wael K, Sensors and actuators : B : chemical 283, 343 (2019). http://doi.org/10.1016/J.SNB.2018.12.039
Abstract: Titanium dioxide (TiO2) is a popular material as host matrix for enzymes. We now evidence that TiO2 can accumulate and retain reactive oxygen species after treatment by hydrogen peroxide (H2O2) and support redox cycling of a phenolic analyte between horseradish peroxidase (HRP) and an electrode. The proposed detection scheme is identical to that of second generation biosensors, but the measuring solution requires no dissolved H2O2. This significantly simplifies the analysis and overcomes issues related to H2O2 being present (or generated) in the solution. The modified electrodes showed rapid stabilization of the baseline, a low noise level, fast realization of a steady-state current response, and, in addition, improved sensitivity and limit of detection compared to the conventional approach, i.e. in the presence of H2O2 in the measuring solution. Hydroquinone, 4-aminophenol, and other phenolic compounds were successfully detected at sub-μM concentrations. Particularly, a linear response in the concentration range between 0.025 and 2 μM and LOD of 24 nM was demonstrated for 4-aminophenol. The proposed sensor design goes beyond the traditional concept with three sensors generations offering a new possibility for the development of enzymatic sensors based on peroxidases and the formation of ROS on titania after treatment with H2O2.
Keywords: A1 Journal article; Laboratory of adsorption and catalysis (LADCA); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 5.401
Times cited: 1
DOI: 10.1016/J.SNB.2018.12.039
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“Fast one-step ultrasensitive detection of toxocara canis antigens by a nanobody-based electrochemical magnetosensor”. Morales-Yanez F, Trashin S, Hermy M, Sariego I, Polman K, Muyldermans S, De Wael K, Analytical chemistry 91, 11582 (2019). http://doi.org/10.1021/ACS.ANALCHEM.9B01687
Abstract: Human toxocariasis (HT) is a cosmopolitan zoonotic disease caused by the migration of the larval stage of the roundworm Toxocara canis. Current HT diagnostic methods do not discriminate between active and past infections. Here, we present a method to quantify Toxocara excretory/secretory antigen, aiming to identify active cases of HT. High specificity is achieved by employing nanobodies (Nbs), single domain antigen binding fragments from camelid heavy chain-only antibodies. High sensitivity is obtained by the design of an electrochemical magnetosensor with an amperometric read-out. Reliable detection of TES antigen at 10 and 30 pg/mL level was demonstrated in phosphate buffered saline and serum, respectively. Moreover, the assay showed no cross-reactivity with other nematode antigens. To our knowledge, this is the most sensitive method to quantify the TES antigen so far. It also has great potential to develop point of care diagnostic systems in other conditions where high sensitivity and specificity are required.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 6.32
Times cited: 2
DOI: 10.1021/ACS.ANALCHEM.9B01687
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“Leaf-deposited semi-volatile organic compounds (SVOCs) : an exploratory study using GCxGC-TOFMS on leaf washing solutions”. Castanheiro A, Joos P, Wuyts K, De Wael K, Samson R, Chemosphere 214, 103 (2019). http://doi.org/10.1016/J.CHEMOSPHERE.2018.09.067
Abstract: Airborne particulate matter (PM) includes semi-volatile organic compounds (SVOCs), which can be deposited on vegetation matrices such as plant leaves. In alternative to air-point measurements or artificial passive substrates, leaf monitoring offers a cost-effective, time-integrating means of assessing local air quality. In this study, leaf washing solutions from ivy (Hedera hibernica) leaves exposed during one-month at different land use classes were explored via comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GCxGC-TOFMS). The composition of leaf-deposited SVOCs, corrected for those of unexposed leaves, was compared against routinely monitored pollutants concentrations (PM10, PM2.5, O3, NO2, SO2) measured at co-located air monitoring stations. The first study on leaf-deposited SVOCs retrieved from washing solutions, herein reported, delivered a total of 911 detected compounds. While no significant land use (rural, urban, industrial, traffic, mixed) effects were observed, increasing exposure time (from one to 28 days) resulted in a higher number and diversity of SVOCs, suggesting cumulative time-integration to be more relevant than local source variations between sites. After one day, leaf-deposited SVOCs were mainly due to alcohols, N-containing compounds, carboxylic acids, esters and lactones, while ketones, diketones and hydrocarbons compounds gained relevance after one week, and phenol compounds after one month. As leaf-deposited SVOCs became overall more oxidized throughout exposure time, SVOCs transformation or degradation at the leaf surface is suggested to be an important phenomenon. This study confirmed the applicability of GCxGC-TOFMS to analyze SVOCs from leaf washing solutions, further research should include validation of the methodology and comparison with atmospheric organic pollutants.
Keywords: A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 4.208
DOI: 10.1016/J.CHEMOSPHERE.2018.09.067
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“Novel phenyl-substituted pyrazinoporphyrazine complexes of rare-earth elements : optimized synthetic protocols and physicochemical properties”. Kosov AD, Dubrinina TV, Borisova NE, Ivanov AV, Drozdov KA, Trashin SA, De Wael K, Kotova MS, Tomilova LG, New journal of chemistry 43, 3153 (2019). http://doi.org/10.1039/C8NJ05939J
Abstract: Novel synthetic protocols based on both template and multi-step methods were developed for phenyl-substituted pyrazinoporphyrazine complexes of rare-earth elements (Y, Eu, Gd, Dy, Er and Lu). p-Hydroquinone was employed as a reaction medium and as a reducing agent in the process of porphyrazine macrocycle formation. Both thermal and microwave irradiation techniques were successfully applied for activation of the template macrocyclization process. An alternative multi-step approach involving the initial stage of free-base ligand formation was realized for the lutetium compound. The target complexes were identified by high-resolution mass spectrometry, infrared spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. Electrochemical behavior in solution and UV-vis absorbance in solutions and films were studied as well. Shifts in the position of the Q band and oxidationreduction potentials in comparison with corresponding phthalocyanine analogues were noticed. Using the IR absorption spectra recorded in the temperature range of 170300 K, the position of the Fermi level of −4.7 ± 0.1 eV and a characteristic energy diagram were obtained for the erbium complex.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 3.269
Times cited: 1
DOI: 10.1039/C8NJ05939J
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“Optimized photoelectrochemical detection of essential drugs bearing phenolic groups”. Neven L, Thiruvottriyur Shanmugam S, Rahemi V, Trashin S, Sleegers N, Carrion EN, Gorun SM, De Wael K, Analytical chemistry 91, 9962 (2019). http://doi.org/10.1021/ACS.ANALCHEM.9B01706
Abstract: The World Health Organization (WHO) model “List of Essential Medicines” includes among indispensable medicines antibacterials and pain and migraine relievers. Monitoring their concentration in the environment, while challenging, is important in the context of antibiotic resistance as well as their production of highly toxic compounds via hydrolysis. Traditional detection methods such as high-performance liquid chromatography (HPLC) or LC combined with tandem mass spectrometry or UV-vis spectroscopy are time-consuming, have a high cost, require skilled operators and are difficult to adapt for field operations. In contrast, (electrochemical) sensors have elicited interest because of their rapid response, high selectivity, and sensitivity as well as potential for on-site detection. Previously, we reported a novel sensor system based on a type II photosensitizer, which combines the advantages of enzymatic sensors (high sensitivity) and photoelectrochemical sensors (easy baseline subtraction). Under red-light illumination, the photosensitizer produces singlet oxygen which oxidizes phenolic compounds present in the sample. The subsequent reduction of the oxidized phenolic compounds at the electrode surface gives rise to a quantifiable photocurrent and leads to the generation of a redox cycle. Herein we report the optimization in terms of pH and applied potential of the photoelectrochemical detection of the hydrolysis product of paracetamol, i.e., 4-aminophenol (4-AP), and two antibacterials, namely, cefadroxil (CFD, beta-lactam antibiotic) and doxycycline (DXC, tetracycline antibiotic). The optimized conditions resulted in a detection limit of 0.2 mu mol L-1 for DXC, but in a 10 times higher sensitivity, 20 nmol L-1, for CFD. An even higher sensitivity, 7 nmol L-1, was noted for 4-AP.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 6.32
Times cited: 2
DOI: 10.1021/ACS.ANALCHEM.9B01706
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“Rapid evaluation of the debromination mechanism of eosin in oil paint by direct analysis in real time and direct infusion-electrospray ionization mass spectrometry”. Alvarez-Martin A, Cleland TP, Kavich GM, Janssens K, Newsome GA, Analytical chemistry 91, 10856 (2019). http://doi.org/10.1021/ACS.ANALCHEM.9B02568
Abstract: Eosin is a synthetic organic colorant prone to fading under the influence of light. On the basis of the growing interest in the understanding of the discoloration mechanism of eosin-based lakes, this study compares the ability of two ultrafast and ultrasensitive mass spectrometry techniques to detect eosin derivatives in complex matrices, such as oil media without the use of conventional separation columns or additional sample preparation protocols. Direct analysis in real time mass spectrometry (DART-MS) and direct infusion electrospray ionization mass spectrometry (DI-ESI-MS) were used to characterize the degradation pathway of eosin in oil media. The analysis protocols developed in this study are applied to discern the degradation mechanism of the lake pigment eosin (comprising the molecule per se complexed to an inorganic substrate) dispersed in linseed oil to create an oil paint. The analysis of oil paints by high resolution MS without an extraction methodology that modifies the system chemistry allowed us to identify the degradation forms without causing any additional fragmentation. Both techniques revealed the primary photodegradation pathway of eosin in linseed oil, and DI-ESI-MS provided additional information on the native conformation of the lake.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 6.32
Times cited: 3
DOI: 10.1021/ACS.ANALCHEM.9B02568
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“Recent advances in analysis of trace elements in environmental samples by X-ray based techniques (IUPAC Technical Report)”. Terzano R, Denecke MA, Falkenberg G, Miller B, Paterson D, Janssens K, Pure and applied chemistry 91, 1029 (2019). http://doi.org/10.1515/PAC-2018-0605
Abstract: Trace elements analysis is a fundamental challenge in environmental sciences. Scientists measure trace elements in environmental media in order to assess the quality and safety of ecosystems and to quantify the burden of anthropogenic pollution. Among the available analytical techniques, X-ray based methods are particularly powerful, as they can quantify trace elements in situ. Chemical extraction is not required, as is the case for many other analytical techniques. In the last few years, the potential for X-ray techniques to be applied in the environmental sciences has dramatically increased due to developments in laboratory instruments and synchrotron radiation facilities with improved sensitivity and spatial resolution. In this report, we summarize the principles of the X-ray based analytical techniques most frequently employed to study trace elements in environmental samples. We report on the most recent developments in laboratory and synchrotron techniques, as well as advances in instrumentation, with a special attention on X-ray sources, detectors, and optics. Lastly, we inform readers on recent applications of X-ray based analysis to different environmental matrices, such as soil, sediments, waters, wastes, living organisms, geological samples, and atmospheric particulate, and we report examples of sample preparation.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 2.626
Times cited: 3
DOI: 10.1515/PAC-2018-0605
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“Transmission and reflection mode macroscopic x-ray powder diffraction imaging for the noninvasive visualization of paint degradation in still life paintings by Jan Davidsz. de Heem”. Vanmeert F, De Keyser N, van Loon A, Klaassen L, Noble P, Janssens K, Analytical chemistry 91, 7153 (2019). http://doi.org/10.1021/ACS.ANALCHEM.9B00328
Abstract: The use of noninvasive chemical imaging techniques is becoming more widespread for the study of cultural heritage artifacts. Recently a mobile instrument for macroscopic X-ray powder diffraction (MA-XRPD) scanning was developed, which is capable of visualizing the distribution of crystalline (pigment) phases in quasi-flat-painted artifacts. In this study, MA-XRPD is used in both transmission and reflection mode for the analysis of three 17th century still life paintings, two paintings by Jan Davidsz. de Heem (1606-1684) and one copy painting after De Heem by an unknown artist. MA-XRPD allowed to reveal and map the presence of in situ-formed alteration products. In the works examined, two rare lead arsenate minerals, schultenite (PbHAsO4) and mimetite (Pb-5(AsO4)(3)Cl), were encountered, both at and below the paint surface; they are considered to be degradation products of the pigments realgar (alpha-As4S4) and orpiment (As2S3). In transmission mode, the depletion of lead white, present in the (second) ground layer, could be seen, illustrating the intrusive nature of this degradation process. In reflection mode, several sulfate salts, palmierite (K2Pb(SO4)(2)), syngenite (K2Ca(SO4)(2)center dot H2O), and gypsum (CaSO4 center dot 2H(2)O), could be detected, in particular, at the (top) surface of the copy painting. Estimates for the information depth and sensitivity of both transmission and reflection mode MA-XRPD for various pigments have been made. The possibility of MA-XRPD to allow for noninvasive identification and visualization of alteration products is considered a significant advantage and unique feature of this method. MA-XRPD can thus provide highly relevant information for assessing the conservation state of artworks and could guide possible future restoration treatments.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 6.32
Times cited: 5
DOI: 10.1021/ACS.ANALCHEM.9B00328
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“Unraveling the mechanisms behind the complete suppression of cocaine electrochemical signals by chlorpromazine, promethazine, procaine, and dextromethorphan”. De Jong M, Sleegers N, Florea A, Van Loon J, van Nuijs ALN, Samyn N, De Wael K, Analytical chemistry 91, 15453 (2019). http://doi.org/10.1021/ACS.ANALCHEM.9B03128
Abstract: The present work investigates the challenges accompanied by the electrochemical cocaine detection in physiological conditions (pH 7) in the presence of chlorpromazine, promethazine, procaine, and dextromethorphan, frequently used cutting agents in cocaine street samples. The problem translates into the absence of the cocaine oxidation signal (signal suppression) when in a mixture with one of these compounds, leading to false negative results. Although a solution to this problem was provided through earlier experiments of our group, the mechanisms behind the suppression are now fundamentally investigated via electrochemical and liquid chromatography quadrupole-time-of-flight mass spectrometry (LC-QTOF-MS) strategies. The latter was used to confirm the passivation of the electrodes due to their interaction with promethazine and chlorpromazine. Electron transfer mechanisms were further identified via linear sweep voltammetry. Next, adsorption experiments were performed on the graphite screen printed electrodes both with and without potential assistance in order to confirm if the suppression of the cocaine signals is due to passivation induced by the cutting agents or their oxidized products. The proposed strategies allowed us to identify the mechanisms of cocaine suppression for each cutting agent mentioned. Suppression due to procaine and dextromethorphan is caused by fouling of the electrode surface by their oxidized forms, while for chlorpromazine and promethazine the suppression of the cocaine signal is related to the strong adsorption of these (nonoxidized) cutting agents onto the graphite electrode surface. These findings provide fundamental insights in possible suppression and other interfering mechanisms using electrochemistry in general not only in the drug detection sector.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Toxicological Centre; Product development
Impact Factor: 6.32
DOI: 10.1021/ACS.ANALCHEM.9B03128
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“X-ray diffraction mapping for cultural heritage science : a review of experimental configurations and applications”. Gonzalez V, Cotte M, Vanmeert F, de Nolf W, Janssens K, Chemistry: a European journal 26, 1703 (2019). http://doi.org/10.1002/CHEM.201903284
Abstract: X-ray diffraction (XRD) mapping consists in the acquisition of XRD patterns at each pixel (or voxel) of an area (or volume). The spatial resolution ranges from the micrometer (mu XRD) to the millimeter (MA-XRD) scale, making the technique relevant for tiny samples up to large objects. Although XRD is primarily used for the identification of different materials in (complex) mixtures, additional information regarding the crystallite size, their orientation, and their in-depth distribution can also be obtained. Through mapping, these different types of information can be located on the studied sample/object. Cultural heritage objects are usually highly heterogeneous, and contain both original and later (degradation, conservation) materials. Their structural characterization is required both to determine ancient manufacturing processes and to evaluate their conservation state. Together with other mapping techniques, XRD mapping is increasingly used for these purposes. Here, the authors review applications as well as the various configurations for XRD mapping (synchrotron/laboratory X-ray source, poly-/monochromatic beam, micro/macro beam, 2D/3D, transmission/reflection mode). On-going hardware and software developments will further establish the technique as a key tool in heritage science.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 5.317
DOI: 10.1002/CHEM.201903284
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“Coupled plasmon modes in 2D gold nanoparticle clusters and their effect on local temperature control”. Borah R, Verbruggen SW, The journal of physical chemistry: C : nanomaterials and interfaces 123, 30594 (2019). http://doi.org/10.1021/ACS.JPCC.9B09048
Abstract: Assemblies of closely separated gold nanoparticles exhibit a strong collective plasmonic response due to coupling of the plasmon modes of the individual nanostructures. In the context of self-assembly of nanoparticles, close-packed two-dimensional (2D) clusters of spherical nanoparticles present an important composite system that promises numerous applications. The present study probes the collective plasmonic characteristics and resulting photothermal behavior of close-packed 2D Au nanoparticle clusters to delineate the effects of the cluster size, interparticle distance, and particle size. Smaller nanoparticles (20 and 40 nm in diameter) that exhibit low individual scattering and high absorption were considered for their relevance to photothermal applications. In contrast to typical literature studies, the present study compares the optical response of clusters of different sizes ranging from a single nanoparticle up to large assemblies of 61 nanoparticles. Increasing the cluster size induces significant changes to the spectral position and optophysical characteristics. Based on the model outcome, an optimal cluster size for maximum absorption per nanoparticle is also determined for enhanced photothermal effects. The effect of the particle size and interparticle distance is investigated to elucidate the nature of interaction in terms of near-field and far-field coupling. The photothermal effect resulting from absorption is compared for different cluster sizes and interparticle distances considering a homogeneous water medium. A strong dependence of the steady-state temperature of the nanoparticles on the cluster size, particle position in the cluster, incident light polarization, and interparticle distance provides new physical insight into the local temperature control of plasmonic nanostructures.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 4.536
DOI: 10.1021/ACS.JPCC.9B09048
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“Image analysis and in situ FTIR as complementary detection tools for photocatalytic soot oxidation”. Van Hal M, Verbruggen SW, Yang X-Y, Lenaerts S, Tytgat T, Chemical engineering journal 367, 269 (2019). http://doi.org/10.1016/J.CEJ.2019.02.154
Abstract: Air pollution, especially particulate matter (PM), is an increasingly urgent problem in urban environments, causing both short and long-term health problems, climate interference and aesthetical problems due to building fouling. Photocatalysis has been shown to be a possible solution to that end. In this work two complementary detection methods for photocatalytic soot oxidation are studied and their advantages and disadvantages are discussed. First, a colour-based digital image analysis method is drastically improved towards an accurate, detailed and straightforward detection tool, that enables simultaneous measurement of the degradation of different grades of soot fouling (for instance a shallow soot haze versus condensed soot deposits). In the next part, a second soot oxidation detection method is presented based on in situ FTIR spectroscopy. This method has the additional advantage of providing more insight into the photocatalytic soot degradation process by monitoring both gaseous and adsorbed intermediates as well as reaction products while the reactions are ongoing. As an illustration, the proposed detection strategies were applied on four different commercially available and synthesized photocatalytic materials. The digital image analysis showed that P25 (Evonik) is the fastest photocatalytic soot degrader of all studied materials for both a uniform soot haze as well as concentrated soot spots. Application of the in situ method showed that for all studied materials adsorbed formate-related surface species were formed and that commercially available ZnO nanopowder has the highest specificity towards complete mineralization into CO2. With this we aim to provide a set of complementary experimental tools for the convenient, reliable, realistic and standardised detection of photocatalytic soot degradation.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 6.216
Times cited: 1
DOI: 10.1016/J.CEJ.2019.02.154
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“Proof of concept of an upscaled photocatalytic multi-tube reactor : a combined modelling and experimental study”. van Walsem J, Roegiers J, Modde B, Lenaerts S, Denys S, Chemical engineering journal 378, 122038 (2019). http://doi.org/10.1016/J.CEJ.2019.122038
Abstract: Three upscaled multi-tube photocatalytic reactors designed for integration into HVAC (Heating, Ventilation and Air Conditioning) systems were proposed and evaluated using a CFD modelling approach, with emphasis on the flow, irradiation and concentration distribution in the reactor and hence, photocatalytic performance. Based on the obtained insights, the best reactor design was selected, further characterized and improved by an additional proof of concept study and eventually converted into practice. Subsequently, the scaled-up prototype was experimentally tested according to the CEN-EN-16846-1 standard (2017) for volatile organic compound (VOC) removal by an external scientific research center. The combined modelling and experimental approach used in this work, leads to essential insights into the design and assessment of photocatalytic reactors. Therefore, this study provides an essential step towards the optimization and commercialization of photocatalytic reactors for HVAC applications.
Keywords: A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 6.216
DOI: 10.1016/J.CEJ.2019.122038
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“A multi-objective optimization-extended techno-economic assessment : exploring the optimal microalgal-based value chain”. Thomassen G, Van Dael M, You F, Van Passel S, Green Chemistry 21, 5945 (2019). http://doi.org/10.1039/C9GC03071A
Abstract: The use of fossil-based products induces a large environmental burden. To lighten this burden, green technologies are required that can replace their fossil-based counterparts. To enable the development of economically viable green technologies, an optimization towards both economic and environmental objectives is required. To perform this multi-objective optimization (MOO), the environmental techno-economic assessment (ETEA) methodology is extended towards a MOO-extended ETEA. The development of this MOO-extended ETEA is the main objective of this manuscript. As an example of a green technology, the concept of microalgae biorefineries is used as a case study to illustrate the MOO-extended ETEA. According to the results, all optimal value chains include open pond cultivation, a membrane for medium recycling and spray drying. The optimal economic value chain uses Nannochloropsis sp. in a one-stage cultivation to produce fish larvae feed, while the optimal environmental design uses Dunaliella salina or Haematococcus pluvialis to produce carotenoids and fertilizer or energy products, by means of anaerobic digestion or gasification. The crucial parameters for both environmental and economic feasibility are the content, price and reference impact of the main end product, the growth parameters and the biomass and carotenoid recovery efficiency alongside the different process steps. By identifying the economic and environmentally optimal algal-based value chain and the crucial drivers, the MOO-extended ETEA provides insights on how algae-based value chains can be developed in the most economic and environmentally-friendly way. For example, the inclusion of a medium recycling step to lower the water and salt consumption is required in all Pareto-optimal scenarios. Another major insight is the requirement of high-value products such as carotenoids or specialty food to obtain and economically and environmentally feasible algal-based value chain. Due to the modular nature of the MOO-extended ETEA, multiple processes can be included or excluded from the superstructure. Although this case study is limited to current microalgae biorefinery technologies, the MOO-extended ETEA can also be used to assess the economic and environmental effect of more innovative technologies. This way, the MOO-extended ETEA provides a methodology to assess the economic and environmental potential of innovative green technologies and shorten their time-to-market.
Keywords: A1 Journal article; Economics; Engineering sciences. Technology; Engineering Management (ENM)
Impact Factor: 9.125
Times cited: 1
DOI: 10.1039/C9GC03071A
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“How to assess the potential of emerging green technologies? Towards a prospective environmental and techno-economic assessment framework”. Thomassen G, Van Dael M, Van Passel S, You F, Green Chemistry 21, 4868 (2019). http://doi.org/10.1039/C9GC02223F
Abstract: For sustainable production and consumption, emerging green technologies need to be optimized towards a minimal environmental impact and a maximal economic impact. In an early stage of technology development, more flexibility is available to adapt the technology. Therefore, a prospective environmental and techno-economic assessment is required. The prospective assessment differs at the different stages of technology development, as also the data availability and accuracy evolves. This paper reviews the different prospective technological, economic and environmental assessment methods which have been used to assess the potential of new green chemical technologies. Based on the current best practices, an overarching framework is introduced to assess the technological, economic and environmental potential of an emerging green chemical technology at the different stages of technology development.
Keywords: A1 Journal article; Engineering sciences. Technology; Engineering Management (ENM)
Impact Factor: 9.125
Times cited: 5
DOI: 10.1039/C9GC02223F
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“Hole-induced spontaneous mutual annihilation of dislocation pairs”. Wu Y, Chen G, Yu J, Wang D, Ma C, Li C, Pennycook SJ, Yan Y, Wei S-H, The journal of physical chemistry letters 10, 7421 (2019). http://doi.org/10.1021/ACS.JPCLETT.9B02918
Abstract: Dislocations are always observed during crystal growth, and it is usually desirable to reduce the dislocation density in high-quality crystals. Here, the annihilation process of the 30 degrees Shockley partial dislocation pairs in CdTe is studied by first-principles calculations. We found that the dislocations can glide relatively easily due to the weak local bonding. Our systematic study of the slipping mechanism of the dislocations suggests that the energy barrier for the annihilation process is low. Band structure calculations reveal that the band bending caused by the charge transfer between the two dislocation cores depends on the core-core distance. A simple linear model is proposed to describe the mechanism of formation of the dislocation pair. More importantly, we demonstrate that hole injection can affect the core structure, increase the mobility, and eventually trigger a spontaneous mutual annihilation, which could be employed as a possible facile way to reduce the dislocation density.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 9.353
DOI: 10.1021/ACS.JPCLETT.9B02918
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“How membrane lipids influence plasma delivery of reactive oxygen species into cells and subsequent DNA damage : an experimental and computational study”. Van der Paal J, Hong S-H, Yusupov M, Gaur N, Oh J-S, Short RD, Szili EJ, Bogaerts A, Physical chemistry, chemical physics 21, 19327 (2019). http://doi.org/10.1039/C9CP03520F
Abstract: The mechanisms of plasma in medicine are broadly attributed to plasma-derived reactive oxygen and nitrogen species (RONS). In order to exert any intracellular effects, these plasma-derived RONS must first traverse a major barrier in the cell membrane. The cell membrane lipid composition, and thereby the magnitude of this barrier, is highly variable between cells depending on type and state (e.g. it is widely accepted that healthy and cancerous cells have different membrane lipid compositions). In this study, we investigate how plasma-derived RONS interactions with lipid membrane components can potentially be exploited in the future for treatment of diseases. We couple phospholipid vesicle experiments, used as simple cell models, with molecular dynamics (MD) simulations of the lipid membrane to provide new insights into how the interplay between phospholipids and cholesterol may influence the response of healthy and diseased cell membranes to plasma-derived RONS. We focus on the (i) lipid tail saturation degree, (ii) lipid head group type, and (iii) membrane cholesterol fraction. Using encapsulated molecular probes, we study the influence of the above membrane components on the ingress of RONS into the vesicles, and subsequent DNA damage. Our results indicate that all of the above membrane components can enhance or suppress RONS uptake, depending on their relative concentration within the membrane. Further, we show that higher RONS uptake into the vesicles does not always correlate with increased DNA damage, which is attributed to ROS reactivity and lifetime. The MD simulations indicate the multifactorial chemical and physical processes at play, including (i) lipid oxidation, (ii) lipid packing, and (iii) lipid rafts formation. The methods and findings presented here provide a platform of knowledge that could be leveraged in the development of therapies relying on the action of plasma, in which the cell membrane and oxidative stress response in cells is targeted.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.123
Times cited: 1
DOI: 10.1039/C9CP03520F
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“Mechanistic studies of gas reactions with multicomponent solids : what can we learn by combining NAP XPS and atomic resolution STEM/EDX?”.Sirotina AP, Callaert C, Volykhov AA, Frolov AS, Sanchez-Barriga J, Knop-Gericke A, Hadermann J, Yashina LV, The journal of physical chemistry: C : nanomaterials and interfaces 123, 26201 (2019). http://doi.org/10.1021/ACS.JPCC.9B05052
Abstract: Rapid development of experimental techniques has enabled real time studies of solid gas reactions at the level reaching the atomic scale. In the present paper, we focus on a combination of atomic resolution STEM/EDX, which visualizes the reaction zone, and near ambient pressure (NAP) XPS, which collects information for a surface layer of variable thickness under reaction conditions. We compare the behavior of two affined topological insulators, Bi2Te3 and Sb2Te3. We used a simple reaction with molecular oxygen occurring at 298 K, which is of practical importance to avoid material degradation. Despite certain limitations, a combination of in situ XPS and ex situ cross-sectional STEM/EDX allowed us to obtain a self-consistent picture of the solid gas reaction mechanism for oxidation of Sb2Te3 and Bi2Te3 crystals, which includes component redistribution between the oxide and the subsurface layer and Te segregation with formation of a thin ordered layer at the interface. The process is multistep in case of both compounds. At the very beginning of the oxidation process the reactivity is determined by the energy benefit of the corresponding element oxygen bond formation. Further in the oxidation process, the behavior of these two compounds becomes similar and features component redistribution between the oxide and the subsurface layer.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 4.536
DOI: 10.1021/ACS.JPCC.9B05052
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“Reactivity and stability of plasma-generated oxygen and nitrogen species in buffered water solution: a computational study”. Heirman P, Van Boxem W, Bogaerts A, Physical chemistry, chemical physics 21, 12881 (2019). http://doi.org/10.1039/C9CP00647H
Abstract: Plasma-treated liquids have great potential for biomedical applications. However, insight into the underlying mechanisms and the exact chemistry is still scarce. In this study, we present the combination of a 0D chemical kinetics and a 2D fluid dynamics model to investigate the plasma treatment of a buffered water solution with the kINPen (R) plasma jet. Using this model, we calculated the gas and liquid flow profiles and the transport and chemistry of all species in the gas and the liquid phase. Moreover, we evaluated the stability of the reactive oxygen and nitrogen species after plasma treatment. We found that of all species, only H2O2, HNO2/NO2-, and HNO3/NO3- are stable in the buffered solution after plasma treatment. This is because both their production and loss processes in the liquid phase are dependent on short-lived radicals (e.g. OH, NO, and NO2). Apart from some discrepancy in the absolute values of the concentrations, which can be explained by the model, all general trends and observations in our model are in qualitative agreement with experimental data and literature.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.123
Times cited: 7
DOI: 10.1039/C9CP00647H
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“Vertical van der Waals heterostructure of single layer InSe and SiGe”. Eren I, Ozen S, Sozen Y, Yagmurcukardes M, Sahin H, The journal of physical chemistry: C : nanomaterials and interfaces 123, 31232 (2019). http://doi.org/10.1021/ACS.JPCC.9B06404
Abstract: We present a first-principles investigation on the stability, electronic structure, and mechanical response of ultrathin heterostructures composed of single layers of InSe and SiGe. First, by performing total energy optimization and phonon calculations, we show that single layers of InSe and SiGe can form dynamically stable heterostructures in 12 different stacking types. Valence and conduction band edges of the heterobilayers form a type-I heterojunction having a tiny band gap ranging between 0.09 and 0.48 eV. Calculations on elastic-stiffness tensor reveal that two mechanically soft single layers form a heterostructure which is stiffer than the constituent layers because of relatively strong interlayer interaction. Moreover, phonon analysis shows that the bilayer heterostructure has highly Raman active modes at 205.3 and 43.7 cm(-1), stemming from the out-of-plane interlayer mode and layer breathing mode, respectively. Our results show that, as a stable type-I heterojunction, ultrathin heterobilayer of InSe/SiGe holds promise for nanoscale device applications.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 4.536
DOI: 10.1021/ACS.JPCC.9B06404
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“Magnetic properties of La3Ni2Sb Ta Nb1––O9, from relaxor to spin glass”. Chin C–M, Battle PD, Hunter EC, Avdeev M, Hendrickx M, Hadermann J, Journal of solid state chemistry (Print) 273, 175 (2019). http://doi.org/10.1016/j.jssc.2019.02.044
Abstract: Neutron diffraction experiments conducted at 5 K in a magnetic field 0 < H/kOe < 50 have shown that the monoclinic perovskite La3Ni2TaO9 behaves as a relaxor ferromagnet. Compositions in the series La3Ni2SbxTayNb1–x–yO9 have been synthesized in polycrystalline form. Electron microscopy, X–ray diffraction and neutron diffraction have shown that the solid solutions are largely homogeneous and monophasic. Magnetometry and neutron diffraction have shown that the relaxor magnetisation persists in low fields when x + y = 1 but is rapidly diminished by the introduction of niobium. This change in magnetic behaviour is ascribed to the differences in the d–orbital energies of Sb5+, Nb5+ and Ta5+.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
DOI: 10.1016/j.jssc.2019.02.044
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“Phase transformation behavior of a two-dimensional zeolite”. Bae J, Cichocka MO, Zhang Y, Bacsik Z, Bals S, Zou X, Willhammar T, Hong SB, Angewandte Chemie: international edition in English 58, 10230 (2019). http://doi.org/10.1002/ANIE.201904825
Abstract: Understanding the molecular-level mechanisms of phase transformation in solids is of fundamental interest for functional materials such as zeolites. Two-dimensional (2D) zeolites, when used as shape-selective catalysts, can offer improved access to the catalytically active sites and a shortened diffusion length in comparison with their 3D analogues. However, few materials are known to maintain both their intralayer microporosity and structure during calcination for organic structure-directing agent (SDA) removal. Herein we report that PST-9, a new 2D zeolite which has been synthesized via the multiple inorganic cation approach and fulfills the requirements for true layered zeolites, can be transformed into the small-pore zeolite EU-12 under its crystallization conditions through the single-layer folding process, but not through the traditional dissolution/recrystallization route. We also show that zeolite crystal growth pathway can differ according to the type of organic SDAs employed.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 2
DOI: 10.1002/ANIE.201904825
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“Bio-based aromatic amines from lignin-derived monomers”. Blondiaux E, Bomon J, Smolen M, Kaval N, Lemière F, Sergeyev S, Diels L, Sels B, Maes BUW, ACS Sustainable Chemistry and Engineering 7, 6906 (2019). http://doi.org/10.1021/ACSSUSCHEMENG.8B06467
Abstract: A new approach to synthesize valuable 3,4-dialkoxyanilines and alkyl propionates from lignin-derived 4-propylguaiacol and -catechol with overall isolated yields up to 65% has been described. The strategy is based on the introduction of nitrogen via a Beckmann rearrangement. Amino introduction therefore coincides with a C-defunctionalization reaction; overall a replacement of the propyl chain by an amino group is obtained. The process only requires cheap bulk chemicals as reagents/reactants and does not involve column chromatography to purify the reaction products. Furthermore, all carbon atoms from the biorenewable lignin-derived monomers are transformed into valuable compounds. Greenness was assessed by performing a Green Metrics analysis on two dialkoxyanilines. A comparison was made with literature routes for these compounds starting from a petrochemical substrate.
Keywords: A1 Journal article; Engineering sciences. Technology; Organic synthesis (ORSY); Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1021/ACSSUSCHEMENG.8B06467
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“CFD-modelling of activated carbon fibers for indoor air purification”. Roegiers J, Denys S, Chemical engineering journal 365, 80 (2019). http://doi.org/10.1016/J.CEJ.2019.02.007
Abstract: Activated carbon fibers for indoor air purification were investigated by means of pressure drop and adsorption capacity. The Darcy-Forchheimer law combined with Computational Fluid Dynamics (CFD) modelling was deployed to simulate the pressure drop over an activated carbon fiber (ACF) filter with varying filter thickness. The CFD model was later combined with adsorption modelling to simulate breakthrough profiles of acetaldehyde adsorption on the ACF-filter. The adsorption model incorporates mass transfer resistance and adsorption equilibrium. It assumes local equilibrium between gas phase and solid phase. The latter was investigated for three different adsorption isotherms: linear, Langmuir and Freundlich adsorption. Successful agreement between model simulations and experimental data was obtained, using the Freundlich adsorption model. The numerical model could provide valuable insights and allows to continuously improve the design of filtration devices.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1016/J.CEJ.2019.02.007
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