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“Gate-tuned anomalous Hall effect driven by Rashba splitting in intermixed LaAlO3/GdTiO3/SrTiO3”. Lebedev N, Stehno M, Rana A, Reith P, Gauquelin N, Verbeeck J, Hilgenkamp H, Brinkman A, Aarts J, Scientific Reports 11, 10726 (2021). http://doi.org/10.1038/s41598-021-89767-3
Abstract: The Anomalous Hall Effect (AHE) is an important quantity in determining the properties and understanding the behaviour of the two-dimensional electron system forming at the interface of SrTiO<sub>3</sub>-based oxide heterostructures. The occurrence of AHE is often interpreted as a signature of ferromagnetism, but it is becoming more and more clear that also paramagnets may contribute to AHE. We studied the influence of magnetic ions by measuring intermixed LaAlO<sub>3</sub>/GdTiO<sub>3</sub>/SrTiO<sub>3</sub>at temperatures below 10 K. We find that, as function of gate voltage, the system undergoes a Lifshitz transition while at the same time an onset of AHE is observed. However, we do not observe clear signs of ferromagnetism. We argue the AHE to be due to the change in Rashba spin-orbit coupling at the Lifshitz transition and conclude that also paramagnetic moments which are easily polarizable at low temperatures and high magnetic fields lead to the presence of AHE, which needs to be taken into account when extracting carrier densities and mobilities.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 4.259
Times cited: 5
DOI: 10.1038/s41598-021-89767-3
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“Gold and silver-catalyzed reductive amination of aromatic carboxylic acids to benzylic amines”. Coeck R, Meeprasert J, Li G, Altantzis T, Bals S, Pidko EA, De Vos DE, Acs Catalysis 11, 7672 (2021). http://doi.org/10.1021/ACSCATAL.1C01693
Abstract: The reductive amination of benzoic acid and its derivatives would be an effective addition to current synthesis methods for benzylamine. However, with current technology it is very difficult to keep the aromaticity intact when starting from benzoic acid, and salt wastes are often generated in the process. Here, we report a heterogeneous catalytic system for such a reductive amination, requiring solely H-2 and NH3 as the reactants. The Ag/TiO2 or Au/TiO2 catalysts can be used multiple times, and very little noble metal is required, only 0.025 mol % Au. The catalysts are bifunctional: the support catalyzes the dehydration of both the ammonium carboxylate to the amide and of the amide to the nitrile, while the sites at the metal-support interface promote the hydrogenation of the in situ generated nitrile. Yields of up to 92% benzylamine were obtained.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Applied Electrochemistry & Catalysis (ELCAT)
Impact Factor: 10.614
Times cited: 16
DOI: 10.1021/ACSCATAL.1C01693
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“Early deformation mechanisms in the shear affected region underneath a copper sliding contact”. Haug C, Ruebeling F, Kashiwar A, Gumbsch P, Kübel C, Greiner C, Nature Communications 11, 839 (2020). http://doi.org/10.1038/S41467-020-14640-2
Abstract: Dislocation mediated plastic deformation decisively influences the friction coefficient and the microstructural changes at many metal sliding interfaces during tribological loading. This work explores the initiation of a tribologically induced microstructure in the vicinity of a copper twin boundary. Two distinct horizontal dislocation traces lines (DTL) are observed in their interaction with the twin boundary beneath the sliding interface. DTL formation seems unaffected by the presence of the twin boundary but the twin boundary acts as an indicator of the occurring deformation mechanisms. Three concurrent elementary processes can be identified: simple shear of the subsurface area in sliding direction, localized shear at the primary DTL and crystal rotation in the layers above and between the DTLs around axes parallel to the transverse direction. Crystal orientation analysis demonstrates a strong compatibility of these proposed processes. Quantitatively separating these different deformation mechanisms is crucial for future predictive modeling of tribological contacts.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 16.6
DOI: 10.1038/S41467-020-14640-2
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“Ab initio prediction of semiconductivity in a novel two-dimensional Sb₂X₃, (X= S, Se, Te) monolayers with orthorhombic structure”. Bafekry A, Mortazavi B, Faraji M, Shahrokhi M, Shafique A, Jappor HR, Nguyen C, Ghergherehchi M, Feghhi SAH, Scientific Reports 11, 10366 (2021). http://doi.org/10.1038/S41598-021-89944-4
Abstract: Sb2S3 and Sb2Se3 are well-known layered bulk structures with weak van der Waals interactions. In this work we explore the atomic lattice, dynamical stability, electronic and optical properties of Sb2S3, Sb2Se3 and Sb2Te3 monolayers using the density functional theory simulations. Molecular dynamics and phonon dispersion results show the desirable thermal and dynamical stability of studied nanosheets. On the basis of HSE06 and PBE/GGA functionals, we show that all the considered novel monolayers are semiconductors. Using the HSE06 functional the electronic bandgap of Sb2S3, Sb2Se3 and Sb2Te3 monolayers are predicted to be 2.15, 1.35 and 1.37 eV, respectively. Optical simulations show that the first absorption coefficient peak for Sb2S3, Sb2Se3 and Sb2Te3 monolayers along in-plane polarization is suitable for the absorption of the visible and IR range of light. Interestingly, optically anisotropic character along planar directions can be desirable for polarization-sensitive photodetectors. Furthermore, we systematically investigate the electrical transport properties with combined first-principles and Boltzmann transport theory calculations. At optimal doping concentration, we found the considerable larger power factor values of 2.69, 4.91, and 5.45 for hole-doped Sb2S3, Sb2Se3, and Sb2Te3, respectively. This study highlights the bright prospect for the application of Sb2S3, Sb2Se3 and Sb2Te3 nanosheets in novel electronic, optical and energy conversion systems.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 4.259
DOI: 10.1038/S41598-021-89944-4
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“Effective Landé, factors for an electrostatically defined quantum point contact in silicene”. Rzeszotarski B, Mrenca-Kolasinska A, Peeters FM, Szafran B, Scientific Reports 11, 19892 (2021). http://doi.org/10.1038/S41598-021-99074-6
Abstract: The transconductance and effective Lande g* factors for a quantum point contact defined in silicene by the electric field of a split gate is investigated. The strong spin-orbit coupling in buckled silicene reduces the g* factor for in-plane magnetic field from the nominal value 2 to around 1.2 for the first-to 0.45 for the third conduction subband. However, for perpendicular magnetic field we observe an enhancement of g* factors for the first subband to 5.8 in nanoribbon with zigzag and to 2.5 with armchair edge. The main contribution to the Zeeman splitting comes from the intrinsic spin-orbit coupling defined by the Kane-Mele form of interaction.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 4.259
DOI: 10.1038/S41598-021-99074-6
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“Electronic transport mechanisms correlated to structural properties of a reduced graphene oxide sponge”. Pinto N, McNaughton B, Minicucci M, Milošević, MV, Perali A, Nanomaterials 11, 2503 (2021). http://doi.org/10.3390/NANO11102503
Abstract: We report morpho-structural properties and charge conduction mechanisms of a foamy “graphene sponge ”, having a density as low as & AP;0.07 kg/m3 and a carbon to oxygen ratio C:O & SIME; 13:1. The spongy texture analysed by scanning electron microscopy is made of irregularly-shaped millimetres-sized small flakes, containing small crystallites with a typical size of & SIME;16.3 nm. A defect density as high as & SIME;2.6 x 1011 cm-2 has been estimated by the Raman intensity of D and G peaks, dominating the spectrum from room temperature down to & SIME;153 K. Despite the high C:O ratio, the graphene sponge exhibits an insulating electrical behavior, with a raise of the resistance value at & SIME;6 K up to 5 orders of magnitude with respect to the room temperature value. A variable range hopping (VRH) conduction, with a strong 2D character, dominates the charge carriers transport, from 300 K down to 20 K. At T < 20 K, graphene sponge resistance tends to saturate, suggesting a temperature-independent quantum tunnelling. The 2D-VRH conduction originates from structural disorder and is consistent with hopping of charge carriers between sp2 defects in the plane, where sp3 clusters related to oxygen functional groups act as potential barriers.</p>
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 3.553
DOI: 10.3390/NANO11102503
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“Cytoglobin Silencing Promotes Melanoma Malignancy but Sensitizes for Ferroptosis and Pyroptosis Therapy Response”. De Backer J, Maric D, Zuhra K, Bogaerts A, Szabo C, Vanden Berghe W, Hoogewijs D, Antioxidants 11, 1548 (2022). http://doi.org/10.3390/antiox11081548
Abstract: Despite recent advances in melanoma treatment, there are still patients that either do not respond or develop resistance. This unresponsiveness and/or acquired resistance to therapy could be explained by the fact that some melanoma cells reside in a dedifferentiated state. Interestingly, this dedifferentiated state is associated with greater sensitivity to ferroptosis, a lipid peroxidation-reliant, iron-dependent form of cell death. Cytoglobin (CYGB) is an iron hexacoordinated globin that is highly enriched in melanocytes and frequently downregulated during melanomagenesis. In this study, we investigated the potential effect of CYGB on the cellular sensitivity towards (1S, 3R)-RAS-selective lethal small molecule (RSL3)-mediated ferroptosis in the G361 melanoma cells with abundant endogenous expression. Our findings show that an increased basal ROS level and higher degree of lipid peroxidation upon RSL3 treatment contribute to the increased sensitivity of CYGB knockdown G361 cells to ferroptosis. Furthermore, transcriptome analysis demonstrates the enrichment of multiple cancer malignancy pathways upon CYGB knockdown, supporting a tumor-suppressive role for CYGB. Remarkably, CYGB knockdown also triggers activation of the NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome and subsequent induction of pyroptosis target genes. Altogether, we show that silencing of CYGB expression modulates cancer therapy sensitivity via regulation of ferroptosis and pyroptosis cell death signaling pathways.
Keywords: A1 Journal article; Pharmacology. Therapy; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT); Proteinscience, proteomics and epigenetic signaling (PPES)
Impact Factor: 7
DOI: 10.3390/antiox11081548
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“Quantifying the variation in the geometries of the outer rims of corolla tubes of Vinca major L”. Wang L, Miao Q, Niinemets Ü, Gielis J, Shi P, Plants 11, 1987 (2022). http://doi.org/10.3390/PLANTS11151987
Abstract: Many geometries of plant organs can be described by the Gielis equation, a polar coordinate equation extended from the superellipse equation, . Here, r is the polar radius corresponding to the polar angle φ; m is a positive integer that determines the number of angles of the Gielis curve when φ ∈ [0 to 2π); and the rest of the symbols are parameters to be estimated. The pentagonal radial symmetry of calyxes and corolla tubes in top view is a common feature in the flowers of many eudicots. However, prior studies have not tested whether the Gielis equation can depict the shapes of corolla tubes. We sampled randomly 366 flowers of Vinca major L., among which 360 had five petals and pentagonal corolla tubes, and six had four petals and quadrangular corolla tubes. We extracted the planar coordinates of the outer rims of corolla tubes (in top view) (ORCTs), and then fitted the data with two simplified versions of the Gielis equation with k = 1 and m = 5: (Model 1), and (Model 2). The adjusted root mean square error (RMSEadj) was used to evaluate the goodness of fit of each model. In addition, to test whether ORCTs are radially symmetrical, we correlated the estimates of n2 and n3 in Model 1 on a log-log scale. The results validated the two simplified Gielis equations. The RMSEadj values for all corolla tubes were smaller than 0.05 for both models. The numerical values of n2 and n3 were demonstrated to be statistically equal based on the regression analysis, which suggested that the ORCTs of V. major are radially symmetrical. It suggests that Model 1 can be replaced by the simpler Model 2 for fitting the ORCT in this species. This work indicates that the pentagonal or quadrangular corolla tubes (in top view) can both be modeled by the Gielis equation and demonstrates that the pentagonal or quadrangular corolla tubes of plants tend to form radial symmetrical geometries during their development and growth.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.3390/PLANTS11151987
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“Nitrogen Fixation by an Arc Plasma at Elevated Pressure to Increase the Energy Efficiency and Production Rate of NOx”. Tsonev I, O’Modhrain C, Bogaerts A, Gorbanev Y, ACS Sustainable Chemistry and Engineering 11, 1888 (2023). http://doi.org/10.1021/acssuschemeng.2c06357
Abstract: Plasma-based nitrogen fixation for fertilizer production is an attractive alternative to the fossil fuel-based industrial processes. However, many factors hinder its applicability, e.g., the commonly observed inverse correlation between energy consumption and production rates or the necessity to enhance the selectivity toward NO2, the desired product for a more facile formation of nitrate-based fertilizers. In this work, we investigated the use of a rotating gliding arc plasma for nitrogen fixation at elevated pressures (up to 3 barg), at different feed gas flow rates and composition. Our results demonstrate a dramatic increase in the amount of NOx produced as a function of increasing pressure, with a record-low EC of 1.8 MJ/(mol N) while yielding a high production rate of 69 g/h and a high selectivity (94%) of NO2. We ascribe this improvement to the enhanced thermal Zeldovich mechanism and an increased rate of NO oxidation compared to the back reaction of NO with atomic oxygen, due to the elevated pressure.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 8.4
DOI: 10.1021/acssuschemeng.2c06357
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“Postplasma Catalytic Model for NO Production: Revealing the Underlying Mechanisms to Improve the Process Efficiency”. Eshtehardi HA, van 't Veer K, Delplancke M-P, Reniers F, Bogaerts A, ACS Sustainable Chemistry and Engineering 11, 1720 (2023). http://doi.org/10.1021/acssuschemeng.2c05665
Abstract: Plasma catalysis is emerging for plasma-assisted gas conversion processes. However, the underlying mechanisms of plasma catalysis are poorly understood. In this work, we present a 1D heterogeneous catalysis model with axial dispersion (i.e., accounting for back-mixing and molecular diffusion of fluid elements in the process stream in the axial direction), for plasma-catalytic NO production from N2/O2 mixtures. We investigate the concentration and reaction rates of each species formed as a function of time and position across the catalyst, in order to determine the underlying mechanisms. To obtain insights into how the performance of the process can be further improved, we also study how changes in the postplasma gas flow composition entering the catalyst bed and in the operation conditions of the catalytic stage affect the performance of NO production.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 8.4
DOI: 10.1021/acssuschemeng.2c05665
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“NH3and HNOxFormation and Loss in Nitrogen Fixation from Air with Water Vapor by Nonequilibrium Plasma”. Vervloessem E, Gromov M, De Geyter N, Bogaerts A, Gorbanev Y, Nikiforov A, ACS Sustainable Chemistry and Engineering 11, 4289 (2023). http://doi.org/10.1021/acssuschemeng.3c00208
Abstract: The current global energy crisis indicated that increasing our
insight into nonfossil fuel nitrogen fixation pathways for synthetic fertilizer
production is more crucial than ever. Nonequilibrium plasma is a good candidate
because it can use N2 or air as a N source and water directly as a H source, instead
of H2 or fossil fuel (CH4). In this work, we investigate NH3 gas phase formation
pathways from humid N2 and especially humid air up to 2.4 mol % H2O (100%
relative humidity at 20 °C) by optical emission spectroscopy and Fouriertransform
infrared spectroscopy. We demonstrate that the nitrogen fixation
capacity is increased when water vapor is added, as this enables HNO2 and NH3
production in both N2 and air. However, we identified a significant loss
mechanism for NH3 and HNO2 that occurs in systems where these species are
synthesized simultaneously; i.e., downstream from the plasma, HNO2 reacts with NH3 to form NH4NO2, which rapidly decomposes
into N2 and H2O. We also discuss approaches to prevent this loss mechanism, as it reduces the effective nitrogen fixation when not
properly addressed and therefore should be considered in future works aimed at optimizing plasma-based N2 fixation. In-line removal
of HNO2 or direct solvation in liquid are two proposed strategies to suppress this loss mechanism. Indeed, using liquid H2O is
beneficial for accumulation of the N2 fixation products. Finally, in humid air, we also produce NH4NO3, from the reaction of HNO3
with NH3, which is of direct interest for fertilizer application.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 8.4
DOI: 10.1021/acssuschemeng.3c00208
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“Postplasma Catalytic Model for NO Production: Revealing the Underlying Mechanisms to Improve the Process Efficiency”. Eshtehardi HA, Van ‘t Veer K, Delplancke M-P, Reniers F, Bogaerts A, ACS Sustainable Chemistry and Engineering 11, 1720 (2023). http://doi.org/10.1021/acssuschemeng.2c05665
Abstract: Plasma catalysis is emerging for plasma-assisted gas conversion
processes. However, the underlying mechanisms of plasma catalysis are poorly
understood. In this work, we present a 1D heterogeneous catalysis model with axial
dispersion (i.e., accounting for back-mixing and molecular diffusion of fluid elements in
the process stream in the axial direction), for plasma-catalytic NO production from
N2/O2 mixtures. We investigate the concentration and reaction rates of each species
formed as a function of time and position across the catalyst, in order to determine the
underlying mechanisms. To obtain insights into how the performance of the process
can be further improved, we also study how changes in the postplasma gas flow
composition entering the catalyst bed and in the operation conditions of the catalytic
stage affect the performance of NO production.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 8.4
DOI: 10.1021/acssuschemeng.2c05665
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“Postplasma Catalytic Model for NO Production: Revealing the Underlying Mechanisms to Improve the Process Efficiency”. Eshtehardi HA, Van ‘t Veer K, Delplancke M-P, Reniers F, Bogaerts A, ACS Sustainable Chemistry and Engineering 11, 1720 (2023). http://doi.org/10.1021/acssuschemeng.2c05665
Abstract: Plasma catalysis is emerging for plasma-assisted gas conversion
processes. However, the underlying mechanisms of plasma catalysis are poorly
understood. In this work, we present a 1D heterogeneous catalysis model with axial
dispersion (i.e., accounting for back-mixing and molecular diffusion of fluid elements in
the process stream in the axial direction), for plasma-catalytic NO production from
N2/O2 mixtures. We investigate the concentration and reaction rates of each species
formed as a function of time and position across the catalyst, in order to determine the
underlying mechanisms. To obtain insights into how the performance of the process
can be further improved, we also study how changes in the postplasma gas flow
composition entering the catalyst bed and in the operation conditions of the catalytic
stage affect the performance of NO production.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 8.4
DOI: 10.1021/acssuschemeng.2c05665
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“Comparison of two simplified versions of the Gielis equation for describing the shape of bamboo leaves”. Yao W, Niinemets Ü, Yao W, Gielis J, Schrader J, Yu K, Shi P, Plants 11, 3058 (2022). http://doi.org/10.3390/PLANTS11223058
Abstract: Bamboo is an important component in subtropical and tropical forest communities. The plant has characteristic long lanceolate leaves with parallel venation. Prior studies have shown that the leaf shapes of this plant group can be well described by a simplified version (referred to as SGE-1) of the Gielis equation, a polar coordinate equation extended from the superellipse equation. SGE-1 with only two model parameters is less complex than the original Gielis equation with six parameters. Previous studies have seldom tested whether other simplified versions of the Gielis equation are superior to SGE-1 in fitting empirical leaf shape data. In the present study, we compared a three-parameter Gielis equation (referred to as SGE-2) with the two-parameter SGE-1 using the leaf boundary coordinate data of six bamboo species within the same genus that have representative long lanceolate leaves, with >300 leaves for each species. We sampled 2000 data points at approximately equidistant locations on the boundary of each leaf, and estimated the parameters for the two models. The root–mean–square error (RMSE) between the observed and predicted radii from the polar point to data points on the boundary of each leaf was used as a measure of the model goodness of fit, and the mean percent error between the RMSEs from fitting SGE-1 and SGE-2 was used to examine whether the introduction of an additional parameter in SGE-1 remarkably improves the model’s fitting. We found that the RMSE value of SGE-2 was always smaller than that of SGE-1. The mean percent errors among the two models ranged from 7.5% to 20% across the six species. These results indicate that SGE-2 is superior to SGE-1 and should be used in fitting leaf shapes. We argue that the results of the current study can be potentially extended to other lanceolate leaf shapes.
Keywords: A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.3390/PLANTS11223058
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“Epitaxial growth of the candidate ferroelectric Rashba material SrBiO3by pulsed laser deposition”. Verdierre G, Gauquelin N, Jannis D, Birkhölzer YA, Mallik S, Verbeeck J, Bibes M, Koster G, APL materials 11, 031109 (2023). http://doi.org/10.1063/5.0138222
Abstract: Among oxides, bismuthates have been gaining much interest due to their unique features. In addition to their superconducting properties, they show potential for applications as topological insulators and as possible spin-to-charge converters. After being first investigated in their bulk form in the 1980s, bismuthates have been successfully grown as thin films. However, most efforts have focused on BaBiO<sub>3</sub>, with SrBiO<sub>3</sub>receiving only little attention. Here, we report the growth of epitaxial films of SrBiO<sub>3</sub>on both TiO<sub>2</sub>-terminated SrTiO<sub>3</sub>and NdO-terminated NdScO<sub>3</sub>substrates by pulsed laser deposition. SrBiO<sub>3</sub>has a pseudocubic lattice constant of ∼4.25 Å and grows relaxed on NdScO<sub>3</sub>. Counter-intuitively, it grows with a slight tensile strain on SrTiO<sub>3</sub>despite a large lattice mismatch, which should induce compressive strain. High-resolution transmission electron microscopy reveals that this occurs as a consequence of structural domain matching, with blocks of 10 SrBiO<sub>3</sub>unit planes matching blocks of 11 SrTiO<sub>3</sub>unit planes. This work provides a framework for the synthesis of high quality perovskite bismuthates films and for the understanding of their interface interactions with homostructural substrates.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 6.1
DOI: 10.1063/5.0138222
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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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“Co-precipitation with iron hydroxide and X-ray fluorescence analysis of trace metals in water”. Chakravorty R, Van Grieken R, International journal of environmental analytical chemistry 11, 67 (1982). http://doi.org/10.1080/03067318208071563
Abstract: Preconcentration of transition trace ions by coprecipitation on iron-hydroxide has been combined with energy-dispersive X-ray fluorescence for environmental water analysis. The optimized preconcentration procedure implies adding 2 mg of iron to a 200 ml water sample, adding dilute NaOH up to pH 9, filtering off on a Nuclepore membrane after a 1 h equilibration time, and analyzing. Quantitative recoveries could then be obtained for Ni, Cu, Zn and Pb, e.g. at the 10 μg/l level in waters of varying salinity while Mn was partially collected. (In fact, for a given problem the iron carrier amount can be adjusted to obtain a satisfactory compromise between high recovery and low detection limit). The precision is 7-8% at the 10 μg/l level, and the detection limits are in the 0.5-1 μg/l range. Various environmental water samples are analysed by way of illustration.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1080/03067318208071563
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“Linking bi-metal distribution patterns in porous carbon nitride fullerene to its catalytic activity toward gas adsorption”. Nematollahi P, Neyts EC, Nanomaterials 11, 1794 (2021). http://doi.org/10.3390/NANO11071794
Abstract: Immobilization of two single transition metal (TM) atoms on a substrate host opens numerous possibilities for catalyst design. If the substrate contains more than one vacancy site, the combination of TMs along with their distribution patterns becomes a design parameter potentially complementary to the substrate itself and the bi-metal composition. By means of DFT calculations, we modeled three dissimilar bi-metal atoms (Ti, Mn, and Cu) doped into the six porphyrin-like cavities of porous C24N24 fullerene, considering different bi-metal distribution patterns for each binary complex, viz. TixCuz@C24N24, TixMny@C24N24, and MnyCuz@C24N24 (with x, y, z = 0-6). We elucidate whether controlling the distribution of bi-metal atoms into the C24N24 cavities can alter their catalytic activity toward CO2, NO2, H-2, and N-2 gas capture. Interestingly, Ti2Mn4@C24N24 and Ti2Cu4@C24N24 complexes showed the highest activity and selectively toward gas capture. Our findings provide useful information for further design of novel few-atom carbon-nitride-based catalysts.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.553
DOI: 10.3390/NANO11071794
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“Major ionic species in size-segregated aerosols and associated gaseous pollutants at a coastal site on the Belgian North Sea”. Horemans B, Krata A, Buczyńska AJ, Dirtu AC, van Meel K, Van Grieken R, Bencs L, Journal of environmental monitoring 11, 670 (2009). http://doi.org/10.1039/B815059A
Abstract: The chemical composition of airborne particulate matter (PM) was studied at a coastal region near De Haan, Belgium, during a winterspring and a summer campaign in 2006. The major ionic components of size-segregated PM, i.e. NH4+, Na+, K+, Mg2+, Ca2+, Cl-, NO3-, and SO42-, and related gaseous pollutants (SO2, NO2, NH3, HNO2, and HNO3) were monitored on a daily basis. Air mass backward-trajectories aided in evaluating the origin of the diurnal pollution load. This was characterised with high levels of fine secondary inorganic aerosols (NH4+, NO3-, and non-sea-salt SO42-) for continental air masses, and sea-salts as the dominant species in coarse maritime aerosols. Seasonal variations in the level of major ionic species were explained by weather conditions and the release of dimethyl sulfide from marine regions. This species was responsible for an increased sea-salt Cl- depletion during summer (56%), causing elevated levels of HCl. Neutralisation ratios for the coarse fraction (0.60.8) suggested a depleted NH4+ level, while that for the fine fraction (1.11.3) had definitely an excess of NH4+, formed by the neutralisation of HCl. The results of factor analysis and the extent of SO2 oxidation indicated that the major ionic species originated from both local and remote sources, classifying the Belgian coastal region as a combined sourcereceptor area of air pollution.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1039/B815059A
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“Optimization of secondary cathode thickness for direct current glow discharge mass spectrometric analysis of glass”. Schelles W, de Gendt S, Van Grieken RE, Journal of analytical atomic spectrometry 11, 937 (1996). http://doi.org/10.1039/JA9961100937
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1039/JA9961100937
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“Protection of stone monuments using a brushing treatment with ammonium oxalate”. Mudronja D, Vanmeert F, Fazinic S, Janssens K, Tibljas D, Desnica V, Coatings 11, 379 (2021). http://doi.org/10.3390/COATINGS11040379
Abstract: Stone monuments and buildings are susceptible to weathering. Carbonate-based stones are especially vulnerable in acidic environments, whereas magmatic acidic stones are more susceptible to chemical weathering in basic environments. To slow down surface corrosion of limestone and marble artworks/buildings, protective coatings which inhibit calcite dissolution have been proposed. In this work, samples from two stone types with different porosity were treated with ammonium oxalate (AmOx) to create a protective layer of calcium oxalate (CaOx) using the previously developed brushing method. Two different synchrotron microscopy experiments were performed to determine its protective capability. X-ray powder diffraction (SR-mu-XRPD) in transmission geometry allowed visualization of the distributions of calcium carbonate and oxalates along the sample depths. In a second step, X-ray fluorescence (SR-mu-XRF) was used to check the efficiency/integrity of the protective surface coating layer. This was done by measuring the sulfur distribution on the stone surface after exposing the protected stones to sulfuric acid. XRPD showed the formation of a protective oxalate layer with a thickness of 5-15 mu m on the less porous stone, while a 20-30 mu m thick layer formed on the more porous stone. The XRF study showed that the optimal treatment time depends on the stone porosity. Increasing the treatment time from 1 to 3 h resulted in a decreased efficiency of the protective layer for the low porosity stone. We assume that this is due to the formation of vertical channels (cracks) in the protective layer.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 2.175
DOI: 10.3390/COATINGS11040379
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“Real-time FO-SPR monitoring of solid-phase DNAzyme cleavage activity for cutting-edge biosensing”. Peeters B, Daems D, Van der Donck T, Delport F, Lammertyn J, ACS applied materials and interfaces 11, 6759 (2019). http://doi.org/10.1021/ACSAMI.8B18756
Abstract: DNA nanotechnology has a great potential in biosensor design including nanostructuring of the biosensor surface through DNA origami, target recognition by means of aptamers, and DNA-based signal amplification strategies. In this paper, we use DNA nanotechnology to describe for the first time the concept of real-time solid-phase monitoring of DNAzyme cleavage activity for the detection of specific single-stranded DNA (ssDNA) with a fiber optic surface plasmon resonance (FO-SPR) biosensor. Hereto, we first developed a robust ligation strategy for the functionalization of the FO-SPR biosensing surface with ssDNA-tethered gold nanoparticles, serving as the substrate for the DNAzyme. Next, we established a relation between the SPR signal change, due to the cleavage activity of the 10–23 DNAzyme, and the concentration of the DNAzyme, showing faster cleavage kinetics for higher DNAzyme concentrations. Finally, we implemented this generic concept for biosensing of ssDNA target in solution. Hereto, we designed a DNAzyme–inhibitor complex, consisting of an internal loop structure complementary to the ssDNA target, that releases active DNAzyme molecules in a controlled way as a function of the target concentration. We demonstrated reproducible target detection with a theoretical limit of detection of 1.4 nM, proving that the presented ligation strategy is key to a universal DNAzyme-based FO-SPR biosensing concept with promising applications in the medical and agrofood sector.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1021/ACSAMI.8B18756
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“Transport and deposition of airborne pollutants in exhibition areas located in historical buildings: study in Wawel Castle Museum in Cracow, Poland”. Worobiec A, Samek J, Krata A, van Meel K, Krupińska B, Stefaniak EA, Karaszkiewicz P, Van Grieken R, Journal of cultural heritage 11, 354 (2010). http://doi.org/10.1016/J.CULHER.2009.11.009
Abstract: Historical buildings and castles that have been turned nowadays into museums, as an exhibition area for precious cultural heritage (CH) items, need more attention since they are CH objects by themselves. Moreover, the preservation techniques require often, significant interventions; however such changes are not always possible or are very limited. The aim of the present study was to investigate the influence of outdoor air pollution on the composition of particulate matter and gases inside the museum of Wawel Castle in Cracow, Poland. During this study a combination of micro and trace analysis techniques were applied, including energy dispersive X-ray fluorescence (EDXRF) and electron probe microanalysis (EPMA). An intensive transport of air pollutants coupled with accumulation of the particles inside the museum was noticed (considerably higher in winter than summer). A high content of carbon and organic matter agglomerated with inorganic particles was determined. Those particles are of special concern because of their adhesive properties and reactivity. It was also noted that the conditions inside the museum favour the reaction of the particles with gaseous pollutants. It was especially the case for nitrate particles.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Laboratory Experimental Medicine and Pediatrics (LEMP)
DOI: 10.1016/J.CULHER.2009.11.009
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“High thermoelectric figure of merit in p-type Mg₃Si₂Te₆: role of multi-valley bands and high anharmonicity”. Pandey T, Peeters FM, Milošević, MV, Journal of materials chemistry C : materials for optical and electronic devices 11, 11185 (2023). http://doi.org/10.1039/D3TC02169F
Abstract: Silicon-based materials are attractive for thermoelectric applications due to their thermal stability, chemical inertness, and natural abundance of silicon. Here, using a combination of first-principles and Boltzmann transport calculations we report the thermoelectric properties of the recently synthesized compound Mg3Si2Te6. Our analysis reveals that Mg3Si2Te6 is a direct bandgap semiconductor with a bandgap of 1.6 eV. The combination of heavy and light valence bands, along with a high valley degeneracy, results in a large power factor under p-type doping. We also find that Mg is weakly bonded both within and between the layers, leading to low phonon group velocities. The vibrations of the Mg atoms are localized and make a significant contribution to phonon-phonon scattering. This high anharmonicity, coupled with low phonon group velocity, results in a low lattice thermal conductivity of & kappa;(l) = 0.5 W m(-1) K-1 at room temperature, along the cross-plane direction. Combining excellent electronic transport properties and low & kappa;(l), p-type Mg3Si2Te6 achieves figure-of-merit (zT) values greater than 1 at temperatures above 600 K. Specifically, a zT of 2.0 is found at 900 K along the cross-plane direction. Our findings highlight the importance of structural complexity and chemical bonding in electronic and phonon transport, providing guiding insights for further design of Si-based thermoelectrics.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 6.4
Times cited: 1
DOI: 10.1039/D3TC02169F
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“Optimizing control strategies for urine nitrification : narrow pH control band enhances process stability and reduces nitrous oxide emissions”. Faust V, Boon N, Ganigué, R, Vlaeminck SE, Udert KM, Frontiers in environmental science 11, 1275152 (2023). http://doi.org/10.3389/FENVS.2023.1275152
Abstract: Nitrification is well-suited for urine stabilization. No base dosage is required if the pH is controlled within an appropriate operating range by urine feeding, producing an ammonium-nitrate fertilizer. However, the process is highly dependent on the selected pH set-points and is susceptible to process failures such as nitrite accumulation or the growth of acid-tolerant ammonia-oxidizing bacteria. To address the need for a robust and reliable process in decentralized applications, two different strategies were tested: operating a two-position pH controller (inflow on/off) with a narrow pH control band at 6.20/6.25 (∆pH = 0.05, narrow-pH) vs. a wider pH control band at 6.00/6.50 (∆pH = 0.50, wide-pH). These variations in pH also cause variations in the chemical speciation of ammonia and nitrite and, as shown, the microbial production of nitrite. It was hypothesized that the higher fluctuations would result in greater microbial diversity and, thus, a more robust process. The diversity of nitrifiers was higher in the wide-pH reactor, while the diversity of the entire microbiome was similar in both systems. However, the wide-pH reactor was more susceptible to tested process disturbances caused by increasing pH or temperature, decreasing dissolved oxygen, or an influent stop. In addition, with an emission factor of 0.47%, the nitrous oxide (N2O) emissions from the wide-pH reactor were twice as high as the N2O emissions from the narrow-pH reactor, most likely due to the nitrite fluctuations. Based on these results, a narrow control band is recommended for pH control in urine nitrification.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.3389/FENVS.2023.1275152
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“Towards a novel strategy for soot removal from water-soluble materials : the synergetic effect of hydrogels and cyclomethicone on gelatine emulsion-based photographs”. Ortega Saez N, Arno R, Marchetti A, Cauberghs S, Janssens K, Van der Snickt G, Al-Emam E, Heritage science 11, 78 (2023). http://doi.org/10.1186/S40494-023-00916-5
Abstract: Gels are a popular cleaning method for paper conservators and a lot of research has been done concerning gel cleaning of paper objects over the last 15 years. Despite the close interconnection between the conservation fields of paper and photographic material, research on using gels for cleaning photographs is very scarce. However, gels can provide an excellent cleaning method for photographic material. Cleaning silver gelatine prints with aqueous solvents is very complex due to the hydrophilic properties and fragility of the gelatine layer which makes mechanical cleaning difficult. The properties of gels ensure better control over the flow and evaporation of the solvent, facilitating the cleaning process. This study is the first insight into the viability of using gellan gum gel and polyvinyl acetate-borax (PVAc-borax) gel to clean contaminants from the surface of silver gelatine photographs. It is based on self-made samples that were artificially aged and contaminated with soot. Water, ethanol (EtOH), and Kodak Photo-flo were studied as solvents to remove the soot from the silver gelatine-based prints. These solvents were loaded into the aforementioned gels and applied to the samples in two different methods. These gel cleaning methods were subsequently compared with traditional cleaning methods. In addition, the usage of cyclomethicone D4 as a protective mask for the gelatine layer was studied. Measuring methods used to evaluate the cleaning were visual comparison, microscopic observation, and densitometry. ATR-FTIR measurements were also conducted to investigate potential side-effects of the cleaning methods on the prints, such as unwanted chemical transformations or the presence of gel residues after the treatments. Most of the gel cleaning methods within this study proved to be inadequate, with the exception of the gellan gum gel loaded with 30% EtOH. It was used as a granulated gel applied mechanically on a print saturated with cyclomethicone (octamethylcyclotetrasiloxane D4). Cyclomethicone proved to be a very effective protective barrier for the water-sensitive gelatine layer with minimal reduction in cleaning effectiveness.
Keywords: A1 Journal article; Engineering sciences. Technology; Art; Antwerp Cultural Heritage Sciences (ARCHES); Antwerp X-ray Imaging and Spectroscopy (AXIS)
Impact Factor: 2.5
DOI: 10.1186/S40494-023-00916-5
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“Plasma-Assisted Dry Reforming of CH4: How Small Amounts of O2Addition Can Drastically Enhance the Oxygenate Production─Experiments and Insights from Plasma Chemical Kinetics Modeling”. Li S, Sun J, Gorbanev Y, van’t Veer K, Loenders B, Yi Y, Kenis T, Chen Q, Bogaerts A, ACS Sustainable Chemistry &, Engineering 11, 15373 (2023). http://doi.org/10.1021/acssuschemeng.3c04352
Abstract: Plasma-based dry reforming of methane (DRM) into
high-value-added oxygenates is an appealing approach to enable
otherwise thermodynamically unfavorable chemical reactions at
ambient pressure and near room temperature. However, it suffers
from coke deposition due to the deep decomposition of CH4. In this
work, we assess the DRM performance upon O2 addition, as well as
varying temperature, CO2/CH4 ratio, discharge power, and gas
residence time, for optimizing oxygenate production. By adding O2,
the main products can be shifted from syngas (CO + H2) toward
oxygenates. Chemical kinetics modeling shows that the improved
oxygenate production is due to the increased concentration of
oxygen-containing radicals, e.g., O, OH, and HO2, formed by electron
impact dissociation [e + O2 → e + O + O/O(1D)] and subsequent
reactions with H atoms. Our study reveals the crucial role of oxygen-coupling in DRM aimed at oxygenates, providing practical
solutions to suppress carbon deposition and at the same time enhance the oxygenates production in plasma-assisted DRM.
Keywords: A1 Journal Article; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ;
Impact Factor: 8.4
DOI: 10.1021/acssuschemeng.3c04352
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“Engineering of hollow periodic mesoporous organosilica nanorods for augmented hydrogen clathrate formation”. Watson G, Kummamuru NB, Verbruggen SW, Perreault P, Houlleberghs M, Martens J, Breynaert E, Van Der Voort P, Journal of materials chemistry A : materials for energy and sustainability 11, 26265 (2023). http://doi.org/10.1039/D3TA05530B
Abstract: Hydrogen (H2) storage, in the form of clathrate hydrates, has emerged as an attractive alternative to classical storage methods like compression or liquefaction. Nevertheless, the sluggish enclathration kinetics along with low gas storage capacities in bulk systems is currently impeding the progress of this technology. To this end, unstirred systems coupled with porous materials have been shown to tackle the aforementioned drawbacks. In line with this approach, the present study explores the use of hydrophobic periodic organosilica nanoparticles, later denoted as hollow ring-PMO (HRPMO), for H2 storage as clathrate hydrates under mild operating conditions (5.56 mol% THF, 7 MPa, and 265–273 K). The surface of the HRPMO nanoparticles was carefully decorated/functionalized with THF-like moieties, which are well-known promoter agents in clathrate formation when applied in classical, homogeneous systems. The study showed that, while the non-functionalized HRPMO can facilitate the formation of binary H2-THF clathrates, the incorporation of surface-bound promotor structures enhances this process. More intriguingly, tuning the concentration of these surface-bound promotor agents on the HRPMO led to a notable effect on solid-state H2 storage capacities. An increase of 3% in H2 storage capacity, equivalent to 0.26 wt%, along with a substantial increase of up to 28% in clathrate growth kinetics, was observed when an optimal loading of 0.14 mmol g−1 of promoter agent was integrated into the HRPMO framework. Overall, the findings from this study highlight that such tuning effects in the solid-state have the potential to significantly boost hydrate formation/growth kinetics and H2 storage capacities, thereby opening new avenues for the ongoing development of H2 clathrates in industrial applications.
Keywords: A1 Journal article; Engineering sciences. Technology
Impact Factor: 11.9
DOI: 10.1039/D3TA05530B
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“Goodenough-Kanamori-Anderson high-temperature ferromagnetism in tetragonal transition-metal xenes”. Yorulmaz U, Šabani D, Sevik C, Milošević, MV, 2D materials 11, 035013 (2024). http://doi.org/10.1088/2053-1583/AD3E08
Abstract: Seminal Goodenough-Kanamori-Anderson (GKA) rules provide an inceptive understanding of the superexchange interaction of two magnetic metal ions bridged with an anion, and suggest fostered ferromagnetic interaction for orthogonal bridging bonds. However, there are no examples of two-dimensional (2D) materials with structure that optimizes the GKA arguments towards enhanced ferromagnetism and its critical temperature. Here we reveal that an ideally planar GKA ferromagnetism is indeed stable in selected tetragonal transition-metal xenes (tTMXs), with Curie temperature above 300 K found in CrC and MnC. We provide the general orbitally-resolved analysis of magnetic interactions that supports the claims and sheds light at the mechanisms dominating the magnetic exchange process in these structures. Furthermore, we propose the set of three GKA-like rules that will guarantee room temperature ferromagetnism. With recent advent of epitaxially-grown tetragonal 2D materials, our findings earmark tTMXs for facilitated spintronic and magnonic applications, or as a desirable magnetic constituent of functional 2D heterostructures.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 5.5
DOI: 10.1088/2053-1583/AD3E08
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“Refining short-range order parameters from the three-dimensional diffuse scattering in single-crystal electron diffraction data”. Poppe R, Roth N, Neder RB, Palatinus L, Iversen BB, Hadermann J, IUCrJ 11, 82 (2024). http://doi.org/10.1107/S2052252523010254
Abstract: Our study compares short-range order parameters refined from the diffuse scattering in single-crystal X-ray and single-crystal electron diffraction data. Nb0.84CoSb was chosen as a reference material. The correlations between neighbouring vacancies and the displacements of Sb and Co atoms were refined from the diffuse scattering using a Monte Carlo refinement in DISCUS. The difference between the Sb and Co displacements refined from the diffuse scattering and the Sb and Co displacements refined from the Bragg reflections in single-crystal X-ray diffraction data is 0.012 (7) angstrom for the refinement on diffuse scattering in single-crystal X-ray diffraction data and 0.03 (2) angstrom for the refinement on the diffuse scattering in single-crystal electron diffraction data. As electron diffraction requires much smaller crystals than X-ray diffraction, this opens up the possibility of refining short-range order parameters in many technologically relevant materials for which no crystals large enough for single-crystal X-ray diffraction are available.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.9
DOI: 10.1107/S2052252523010254
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