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“Dried aerobic heterotrophic bacteria from treatment of food and beverage effluents: Screening of correlations between operation parameters and microbial protein quality”. Muys M, Papini G, Spiller M, Sakarika M, Schwaiger B, Lesueur C, Vermeir P, Vlaeminck SE, Bioresource Technology 307, 123242 (2020). http://doi.org/10.1016/J.BIORTECH.2020.123242
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 11.4
Times cited: 1
DOI: 10.1016/J.BIORTECH.2020.123242
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“Protecting and stimulating effect on the degradation of eosin lakes. Part 1 : lead white and cobalt blue”. Alvarez-Martin A, Janssens K, Microchemical journal 141, 51 (2018). http://doi.org/10.1016/J.MICROC.2018.05.005
Abstract: An important problem encountered during the preservation of paintings and other artworks is the fading of the original colors due to exposure of the colorants to light. This fact is clearly evidenced in some of Vincent Van Gogh's paintings in which an organic red, eosin or geranium lake, is present. The identification of eosin and the characterization of its degradation products in paintings represents a challenge because of (i) the generally low concentration of the pigment remaining after an aging period of ca 100 years, (ii) the scarcity of the paint micro samples available for analysis and the difficulty of obtaining additional ones and (iii) the complexity of the degradation behavior of eosin when it is mixed with organic or inorganic pigments, binding media or varnish. This study presents an accelerated aging experiment of eosin paint models in order to understand better the discoloration process; more specifically the influence of different metals with which eosin forms complexes and of the presence of admixture pigments such as lead white and cobalt blue on the lightfastness of eosin is evaluated. Paint model samples were prepared using eosin, lead white, and cobalt blue in different mixing ratios and were characterized with several techniques before and after aging. The possible formation of intermediate molecular forms during the aging experiment and the influence of pigment ratios on the discoloration process were monitored at periodic intervals using a combination of LTV Visible and attenuated total Reflectance-Fourier transform infrared (ATR-FTIR) spectroscopies. Raman spectroscopy, scanning electron microscopy coupled to energy-dispersive X-ray analysis (SEM-EDX) and optical microscopy (OM) analyses were performed to gain information about the discoloration processes taking place within the paint models. Eosin precipitated on lead, aluminum and potassium/aluminum salts was used. These three lakes showed similar discoloration rates under light exposure. In contrast, the presence and relative abundance of the admixture pigments lead white and cobalt blue had a significant influence on the (speed of the) eosin discoloration process. The presence of lead white and cobalt blue appears to stimulate the eosin degradation. However, the cobalt blue shows less influence in the discoloration process, showing a protective effect during the first stages of the aging. This may be qualitatively explained in terms of the ability of lead white to scatter light towards eosin molecules and the absorption characteristics of cobalt blue in the green range of the electromagnetic spectrum, shielding eosin from incoming light. The color changes observed in the paint reconstructions are similar to discoloration phenomena visible in some Van Gogh paintings and can offer an explanation of the gradual discoloration process that took place over the years. These insights will be helpful to estimate the original hues color used/intended by the artist.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 3.034
Times cited: 3
DOI: 10.1016/J.MICROC.2018.05.005
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“Hole states in nanocups in a magnetic field”. Čukarić, N, Arsoski V, Tadić, M, Peeters FM, Physical review : B : condensed matter and materials physics 85, 235425 (2012). http://doi.org/10.1103/PhysRevB.85.235425
Abstract: The magnetic-field dependence of the hole states in a nanocup, which is composed of a ring (the nanocup rim) that surrounds a disk (the nanocup bottom), is obtained within the Luttinger-Kohn model for the unstrained GaAs/(Al,Ga) As and the strained (In,Ga) As/GaAs systems. Aharonov-Bohm oscillations due to angular momentum transitions of the hole ground state appear with periods that vary with the thickness of the disk. The strain in the (In, Ga) As/GaAs nanocup is sensitive to the disk thickness and favors the spatial localization of the heavy holes inside the disk. Therefore, the angular momentum transitions between the valence-band states disappear for much thinner disks than in the case of the unstrained GaAs/(Al, Ga) As nanocups. In both systems, the oscillations in the energy of the hole ground state are found to disappear for thinner inner layer than in the electron ground-state energy. This is due to the different confining potentials and the mixing between the heavy- and light-hole states. As a consequence, magnetization of the single hole is found to strongly depend on the bottom thickness of the strained (In, Ga) As/GaAs nanocup. Furthermore, we found that the strain can lead to a spatial separation of the electron and the hole, as in type-II band alignment, which is advantageous for the appearance of the excitonic Aharonov-Bohm effect.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 4
DOI: 10.1103/PhysRevB.85.235425
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“Catalyst design by NH4OH treatment of USY zeolite”. Van Aelst J, Verboekend D, Philippaerts A, Nuttens N, Kurttepeli M, Gobechiya E, Haouas M, Sree SP, Denayer JFM, Martens JA, Kirschhock CEA, Taulelle F, Bals S, Baron GV, Jacobs PA, Sels BF, Advanced functional materials 25, 7130 (2015). http://doi.org/10.1002/adfm.201502772
Abstract: Hierarchical zeolites are a class of superior catalysts which couples the intrinsic zeolitic properties to enhanced accessibility and intracrystalline mass transport to and from the active sites. The design of hierarchical USY (Ultra-Stable Y) catalysts is achieved using a sustainable postsynthetic room temperature treatment with mildly alkaline NH4OH ( 0.02(M)) solutions. Starting from a commercial dealuminated USY zeolite (Si/Al = 47), a hierarchical material is obtained by selective and tuneable creation of interconnected and accessible small mesopores (2- 6 nm). In addition, the treatment immediately yields the NH4+ form without the need for additional ion exchange. After NH4OH modification, the crystal morphology is retained, whereas the microporosity and relative crystallinity are decreased. The gradual formation of dense amorphous phases throughout the crystal without significant framework atom leaching rationalizes the very high material yields (>90%). The superior catalytic performance of the developed hierarchical zeolites is demonstrated in the acid-catalyzed isomerization of alpha-pinene and the metal-catalyzed conjugation of safflower oil. Significant improvements in activity and selectivity are attained, as well as a lowered susceptibility to deactivation. The catalytic performance is intimately related to the introduced mesopores, hence enhanced mass transport capacity, and the retained intrinsic zeolitic properties.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 12.124
Times cited: 64
DOI: 10.1002/adfm.201502772
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“Cuboidal supraparticles self-assembled from cubic CsPbBr3 perovskite nanocrystals”. van der Burgt JS, Geuchies JJ, van der Meer B, Vanrompay H, Zanaga D, Zhang Y, Albrecht W, Petukhov AV, Filion L, Bals S, Swart I, Vanmaekelbergh D, The journal of physical chemistry: C : nanomaterials and interfaces 122, 15706 (2018). http://doi.org/10.1021/ACS.JPCC.8B02699
Abstract: Colloidal CsPbBr3 nanocrystals (NCs) have emerged as promising candidates for various opto-electronic applications, such as light-emitting diodes, photodetectors, and solar cells. Here, we report on the self-assembly of cubic NCs from an organic suspension into ordered cuboidal supraparticles (SPs) and their structural and optical properties. Upon increasing the NC concentration or by addition of a nonsolvent, the formation of the SPs occurs homogeneously in the suspension, as monitored by in situ X-ray scattering measurements. The three-dimensional structure of the SPs was resolved through high-angle annular dark-field scanning transmission electron microscopy and electron tomography. The NCs are atomically aligned but not connected. We characterize NC vacancies on superlattice positions both in the bulk and on the surface of the SPs. The occurrence of localized atomic-type NC vacancies-instead of delocalized ones-indicates that NC-NC attractions are important in the assembly, as we verify with Monte Carlo simulations. Even when assembled in SPs, the NCs show bright emission, with a red shift of about 30 meV compared to NCs in suspension.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 4.536
Times cited: 60
DOI: 10.1021/ACS.JPCC.8B02699
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“Crystal growth of the Nowotny chimney ladder phase Fe2Ge3 : exploring new Fe-based narrow-gap semiconductor with promising thermoelectric performance”. Verchenko VY, Wei Z, Tsirlin AA, Callaert C, Jesche A, Hadermann J, Dikarev EV, Shevelkov AV, Chemistry of materials 29, 9954 (2017). http://doi.org/10.1021/ACS.CHEMMATER.7B03300
Abstract: <script type='text/javascript'>document.write(unpmarked('A new synthetic approach based on chemical transport reactions has been introduced to obtain the Nowotny chimney ladder phase Fe2Ge3 in the form of single crystals and polycrystalline powders. The single crystals possess the stoichiometric composition and the commensurate chimney ladder structure of the Ru2Sn3 type in contrast to the polycrystalline samples that are characterized by a complex microstructure. In compliance with the 18-n electron counting rule formulated for T-E intermetallics, electronic structure calculations reveal a narrow-gap semiconducting behavior of Fe2Ge3 favorable for high thermoelectric performance. Measurements of transport and thermoelectric properties performed on the polycrystalline samples confirm the formation of a narrow band gap of similar to 30 meV and reveal high absolute values of the Seebeck coefficient at elevated temperatures. Low glass-like thermal conductivity is observed in a wide temperature range that might be caused by the underlying complex microstructure.'));
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 11
DOI: 10.1021/ACS.CHEMMATER.7B03300
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“Integration of a photoelectrochemical cell in a flow system for quantification of 4-aminophenol with titanium dioxide”. Mendonça CD, Rahemi V, Hereijgers J, Breugelmans T, Machado SAS, De Wael K, Electrochemistry Communications 117, 106767 (2020). http://doi.org/10.1016/J.ELECOM.2020.106767
Abstract: The photoelectrochemical quantification of phenolic compounds such as hydroquinone (HQ) and 4-aminophenol (4-AP) is accomplished by integrating a photoelectrochemical cell into a flow injection analysis (FIA) setup. It is a well-known fact that during the electroanalysis of phenolic compounds, the electrode surface is susceptible to poisoning. However, electrode fouling can be reduced significantly by using the FIA system with periodic washing of the electrode. Reactive oxygen species (ROS), which are generated on the surface of TiO2 under UV light, can oxidize phenolic compounds such as 4-AP. The oxidized form of 4-AP is reduced back at the electrode surface, generating a measurable signal proportional to its concentration. The factors influencing the perfor-mance of the sensor, such as flow rate, applied potential for back reduction and pH, are investigated in detail. In the concentration range 0.0125-1.0 mu M, a linear correlation between the photocurrent and the concentration of 4-AP was observed with a sensitivity of 0.6 A M-1 cm(-2) and a limit of detection of 18 nM. A straightforward analytical methodology for the on-site, highly sensitive and low-cost quantification of phenolic compounds is presented, based on the use of TiO2 in a photoelectrochemical flow cell.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Applied Electrochemistry & Catalysis (ELCAT)
Impact Factor: 5.4
Times cited: 1
DOI: 10.1016/J.ELECOM.2020.106767
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“Evidence from quantum Monte Carlo simulations of large-gap superfluidity and BCS-BEC crossover in double electron-hole layers”. Rios PL, Perali A, Needs RJ, Neilson D, Physical review letters 120, 177701 (2018). http://doi.org/10.1103/PHYSREVLETT.120.177701
Abstract: We report quantum Monte Carlo evidence of the existence of large gap superfluidity in electron-hole double layers over wide density ranges. The superfluid parameters evolve from normal state to BEC with decreasing density, with the BCS state restricted to a tiny range of densities due to the strong screening of Coulomb interactions, which causes the gap to rapidly become large near the onset of superfluidity. The superfluid properties exhibit similarities to ultracold fermions and iron-based superconductors, suggesting an underlying universal behavior of BCS-BEC crossovers in pairing systems.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 8.462
Times cited: 11
DOI: 10.1103/PHYSREVLETT.120.177701
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“Boosting Monte Carlo simulations of spin glasses using autoregressive neural networks”. McNaughton B, Milošević, MV, Perali A, Pilati S, Physical Review E 101, 053312 (2020). http://doi.org/10.1103/PHYSREVE.101.053312
Abstract: The autoregressive neural networks are emerging as a powerful computational tool to solve relevant problems in classical and quantum mechanics. One of their appealing functionalities is that, after they have learned a probability distribution from a dataset, they allow exact and efficient sampling of typical system configurations. Here we employ a neural autoregressive distribution estimator (NADE) to boost Markov chain Monte Carlo (MCMC) simulations of a paradigmatic classical model of spin-glass theory, namely, the two-dimensional Edwards-Anderson Hamiltonian. We show that a NADE can be trained to accurately mimic the Boltzmann distribution using unsupervised learning from system configurations generated using standard MCMC algorithms. The trained NADE is then employed as smart proposal distribution for the Metropolis-Hastings algorithm. This allows us to perform efficient MCMC simulations, which provide unbiased results even if the expectation value corresponding to the probability distribution learned by the NADE is not exact. Notably, we implement a sequential tempering procedure, whereby a NADE trained at a higher temperature is iteratively employed as proposal distribution in a MCMC simulation run at a slightly lower temperature. This allows one to efficiently simulate the spin-glass model even in the low-temperature regime, avoiding the divergent correlation times that plague MCMC simulations driven by local-update algorithms. Furthermore, we show that the NADE-driven simulations quickly sample ground-state configurations, paving the way to their future utilization to tackle binary optimization problems.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.366
Times cited: 15
DOI: 10.1103/PHYSREVE.101.053312
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“Macroscopic X-ray powder diffraction scanning : possibilities for quantitative and depth-selective parchment analysis”. Vanmeert F, de Nolf W, Dik J, Janssens K, Analytical chemistry 90, 6445 (2018). http://doi.org/10.1021/ACS.ANALCHEM.8B00241
Abstract: At or below the surface of painted works of art, valuable information is present that provides insights into an objects past, such as the artists technique and the creative process that was followed or its conservation history but also on its current state of preservation. Various noninvasive techniques have been developed over the past 2 decades that can probe this information either locally (via point analysis) or on a macroscopic scale (e.g., full-field imaging and raster scanning). Recently macroscopic X-ray powder diffraction (MA-XRPD) mapping using laboratory X-ray sources was developed. This method can visualize highly specific chemical distributions at the macroscale (dm(2)). In this work we demonstrate the synergy between the quantitative aspects of powder diffraction and the noninvasive scanning capability of MA-XRPD highlighting the potential of the method to reveal new types of information. Quantitative data derived from a 15th/16th century illuminated sheet of parchment revealed three lead white pigments with different hydrocerussite-cerussite compositions in specific pictorial elements, while quantification analysis of impurities in the blue azurite pigment revealed two distinct azurite types: one rich in barite and one in quartz. Furthermore, on the same artifact, the depth-selective possibilities of the method that stem from an exploitation of the shift of the measured diffraction peaks with respect to reference data are highlighted. The influence of different experimental parameters on the depth-selective analysis results is briefly discussed. Promising stratigraphic information could be obtained, even though the analysis is hampered by not completely understood variations in the unit cell dimensions of the crystalline pigment phases.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 6.32
Times cited: 6
DOI: 10.1021/ACS.ANALCHEM.8B00241
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“Newtonian trajectories : a powerful tool for solving quantum dynamics”. Brosens F, Magnus W, Solid state communications 150, 2102 (2010). http://doi.org/10.1016/j.ssc.2010.09.019
Abstract: Since Ehrenfests theorem, the role and importance of classical paths in quantum dynamics have been examined by several means. Along this line, we show that the classical equations of motion provide a solution to quantum dynamics, if appropriately incorporated into the Wigner distribution function, exactly reformulated in a type of Boltzmann equation. Also the quantum-mechanical features of the canonical ensemble can be studied in this framework of Newtonian dynamics, if the initial distribution function is appropriately constructed from the statistical operator.
Keywords: A1 Journal article; Theory of quantum systems and complex systems; Condensed Matter Theory (CMT)
Impact Factor: 1.554
Times cited: 7
DOI: 10.1016/j.ssc.2010.09.019
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“Interfacial oxidation and photoluminescence of InP-Based core/shell quantum dots”. Tessier MD, Baquero EA, Dupont D, Grigel V, Bladt E, Bals S, Coppel Y, Hens Z, Nayral C, Delpech F, Chemistry of materials 30, 6877 (2018). http://doi.org/10.1021/ACS.CHEMMATER.8B03117
Abstract: Indium phosphide colloidal quantum dots (QDs) are emerging as an efficient cadmium-free alternative for optoelectronic applications. Recently, syntheses based on easy-to-implement aminophosphine precursors have been developed. We show by solid-state nuclear magnetic resonance spectroscopy that this new approach allows oxide-free indium phosphide core or core/shell quantum dots to be made. Importantly, the oxide-free core/shell interface does not help in achieving higher luminescence efficiencies. We demonstrate that in the case of InP/ZnS and InP/ZnSe QDs, a more pronounced oxidation concurs with a higher photoluminescence efficiency. This study suggests that a II-VI shell on a III-V core generates an interface prone to defects. The most efficient InP/ZnS or InP/ZnSe QDs are therefore made with an oxide buffer layer between the core and the shell: it passivates these interface defects but also results in a somewhat broader emission line width.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 74
DOI: 10.1021/ACS.CHEMMATER.8B03117
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“Effect of boundary-induced chirality on magnetic textures in thin films”. Mulkers J, Hals KMD, Leliaert J, Milošević, MV, Van Waeyenberge B, Everschor-Sitte K, Physical review B 98, 064429 (2018). http://doi.org/10.1103/PHYSREVB.98.064429
Abstract: In the quest for miniaturizing magnetic devices, the effects of boundaries and surfaces become increasingly important. Here we show how the recently predicted boundary-induced Dzyaloshinskii-Moriya interaction (DMI) affects the magnetization of ferromagnetic films with a C-infinity v symmetry and a perpendicular magnetic anisotropy. For an otherwise uniformly magnetized film, we find a surface twist when the magnetization in the bulk is canted by an in-plane external field. This twist at the surfaces caused by the boundary-induced DMI differs from the common canting caused by internal DMI observed at the edges of a chiral magnet. Furthermore, we find that the surface twist due to the boundary-induced DMI strongly affects the width of the domain wall at the surfaces. We also find that the skyrmion radius increases in the depth of the film, with the average size of the skyrmion increasing with boundary-induced DMI. This increase suggests that the boundary-induced DMI contributes to the stability of the skyrmion.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 9
DOI: 10.1103/PHYSREVB.98.064429
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“Tuning of the spin-orbit interaction in a quantum dot by an in-plane magnetic field”. Nowak MP, Szafran B, Peeters FM, Partoens B, Pasek WJ, Physical review : B : condensed matter and materials physics 83, 245324 (2011). http://doi.org/10.1103/PhysRevB.83.245324
Abstract: Using an exact-diagonalization approach we show that one- and two-electron InAs quantum dots exhibit an avoided crossing in the energy spectra that is induced by the spin-orbit coupling in the presence of an in-plane external magnetic field. The width of the avoided crossings depends strongly on the orientation of the magnetic field, which reveals the intrinsic anisotropy of the spin-orbit-coupling interactions. We find that for specific orientations of the magnetic field avoided crossings vanish. A value of this orientation can be used to extract the ratio of the strength of Rashba and Dresselhaus interactions. The spin-orbit anisotropy effects for various geometries and orientations of the confinement potential are discussed. Our analysis explains the physics behind the recent measurements performed on a gated self-assembled quantum dot [ S. Takahashi et al. Phys. Rev. Lett. 104 246801 (2010)].
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 27
DOI: 10.1103/PhysRevB.83.245324
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“Defect-directed growth of symmetrically branched metal nanocrystals”. Smith JD, Bladt E, Burkhart JAC, Winckelmans N, Koczkur KM, Ashberry HM, Bals S, Skrabalak SE, Angewandte Chemie-International Edition 59, 943 (2020). http://doi.org/10.1002/ANIE.201913301
Abstract: Branched plasmonic nanocrystals (NCs) have attracted much attention due to electric field enhancements at their tips. Seeded growth provides routes to NCs with defined branching patterns and, in turn, near-field distributions with defined symmetries. Here, a systematic analysis was undertaken in which seeds containing different distributions of planar defects were used to grow branched NCs in order to understand how their distributions direct the branching. Characterization of the products by multimode electron tomography and analysis of the NC morphologies at different overgrowth stages indicate that the branching patterns are directed by the seed defects, with the emergence of branches from the seed faces consistent with minimizing volumetric strain energy at the expense of surface energy. These results contrast with growth of branched NCs from single-crystalline seeds and provide a new platform for the synthesis of symmetrically branched plasmonic NCs.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 16.6
Times cited: 23
DOI: 10.1002/ANIE.201913301
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“Amperometric flow-injection analysis of phenols induced by reactive oxygen species generated under daylight irradiation of titania impregnated with horseradish peroxidase”. Rahemi V, Trashin S, Hafideddine Z, Van Doorslaer S, Meynen V, Gorton L, De Wael K, Analytical Chemistry 92, 3643 (2020). http://doi.org/10.1021/acs.analchem.9b04617
Abstract: Titanium dioxide (TiO2) is a unique material for biosensing applications due to its capability of hosting enzymes. For the first time, we show that TiO2 can accumulate reactive oxygen species (ROS) under daylight irradiation and can support the catalytic cycle of horseradish peroxidase (HRP) without the need of H2O2 to be present in the solution. Phenolic compounds, such as hydroquinone (HQ) and 4-aminophenol (4-AP), were detected amperometrically in flow-injection analysis (FIA) mode via the use of an electrode modified with TiO2 impregnated with HRP. In contrast to the conventional detection scheme, no H2O2 was added to the analyte solution. Basically, the inherited ability of TiO2 to generate reactive oxygen species is used as a strategy to avoid adding H2O2 in the solution during the detection of phenolic compounds. Electron paramagnetic resonance (EPR) spectroscopy indicates the presence of ROS on titania which, in interaction with HRP, initiate the electrocatalysis toward phenolic compounds. The amperometric response to 4-AP was linear in the concentration range between 0.05 and 2 μM. The sensitivity was 0.51 A M–1 cm–2, and the limit of detection (LOD) 26 nM. The proposed sensor design opens new opportunities for the detection of phenolic traces by HRP-based electrochemical biosensors, yet in a more straightforward and sensitive way following green chemistry principles of avoiding the use of reactive and harmful chemical, such as H2O2.
Keywords: A1 Journal article; Laboratory of adsorption and catalysis (LADCA); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 7.4
Times cited: 3
DOI: 10.1021/acs.analchem.9b04617
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“A large area full-field EDXRF imaging system based on a THCOBRA gaseous detector”. Silva ALM, Carvalho ML, Janssens K, Veloso JFCA, Journal of analytical atomic spectrometry 30, 343 (2015). http://doi.org/10.1039/C4JA00301B
Abstract: By taking advantage of the attractive features in terms of gain, position and energy resolution of the 2D-THCOBRA detector, a new large area Full-Field X-ray Fluorescence Imaging (FF-XRFI) system for EDXRF imaging applications was developed. The proposed FF-XRFI system has an active area of 10 x 10 cm(2) and can be used to examine macroscopic samples with a moderately good energy resolution (< 1.6 keV FWHM at 8 keV) and a suitable spatial resolution (similar to 500 mu m FWHM). This combination of characteristics allows us to record elemental distribution maps from the surface of different sample types by combining image and energy information. Two different approaches were used for X-ray optics, one based on a single pinhole and another based on a parallel multiple-hole collimator. To illustrate the system capabilities, some sample examples were imaged and studied.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 3.379
Times cited: 11
DOI: 10.1039/C4JA00301B
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“Risks of atmospheric aerosol for cultural heritage assets in Granada (Spain)”. Cardell C, Urosevic M, Sebastián-Pardo E, Horemans B, Kontozova-Deutsch V, Potgieter-Vermaak S, Bencs L, Anaf KW, De Wael K, Van Grieken R page 45 (2013).
Keywords: H1 Book chapter; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
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“Atomistic simulation of ultra-short pulsed laser ablation of metals with single and double pulses : an investigation of the re-deposition phenomenon”. Foumani AA, Forster DJ, Ghorbanfekr H, Weber R, Graf T, Niknam AR, Applied Surface Science 537, 147775 (2021). http://doi.org/10.1016/J.APSUSC.2020.147775
Abstract: The demand for higher throughput in the processing of materials with ultra-short pulsed lasers has motivated studies on the use of double pulses (DP). It has been observed in such studies that at relatively high time delays between the two pulses, the ablated volume is lower than that for a single pulse (SP). This has been attributed to the shielding of the second pulse and the re-deposition of the material removed by the first pulse. The investigation of re-deposition in copper with the aid of atomistic simulations is the main objective of this study. Nevertheless, a computational investigation of SP-ablation and experimental measurement of the SP-ablation depths and threshold fluence are also covered. The applied computational apparatus comprises a combination of molecular dynamics with the two-temperature model and the Helmholtz wave equation. The analysis of the simulation results shows that the derived quantities like the SP-ablation threshold fluence and the ratio of DP ablation depth to SP-ablation depth are in agreement with the experimental values. An important finding of this study is that the characteristics of the re-deposition process are highly dependent on the fluence.
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.387
Times cited: 2
DOI: 10.1016/J.APSUSC.2020.147775
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“Leaf accumulation of atmospheric dust : biomagnetic, morphological and elemental evaluation using SEM, ED-XRF and HR-ICP-MS”. Castanheiro A, Hofman J, Nuyts G, Joosen S, Spassov S, Blust R, Lenaerts S, De Wael K, Samson R, Atmospheric Environment 221, 117082 (2020). http://doi.org/10.1016/J.ATMOSENV.2019.117082
Abstract: Atmospheric dust deposition on plants enables the collection of site-specific particulate matter (PM). Knowing the morphology and composition of PM aids in disclosing their emitting sources as well as the associated human health risk. Therefore, this study aimed for a leaf-level holistic analysis of dust accumulation on plant leaves. Plant species (ivy and strawberry) with distinct leaf macro- and micro-morphology were exposed during 3 months at a moderate road traffic site in Antwerp, Belgium. Leaves collected every three weeks were analyzed for their magnetic signature, morphology and elemental content, by a combination of techniques (biomagnetic analyses, ED-XRF, HR-ICP-MS, SEM). Dust accumulation on the leaves was observed both visually (SEM) and magnetically, while the metal enrichment was limited (only evident for Cr) and more variable over time. Temporal dynamics during the second half of the exposure period, due to precipitation events and reduction of atmospheric pollution input, were evidenced in our results (elements/magnetically/SEM). Ivy accumulated more dust than strawberry leaves and seemed less susceptible to wash-off, even though strawberry leaves contain trichomes and a rugged micromorphology, leaf traits considered to be important for capturing PM. The magnetic enrichment (in small-grained, SD/PSD magnetite particles), on the other hand, was not species-specific, indicating a common contributing source. Variations in pollution contributions, meteorological phenomena, leaf traits, particle deposition (and encapsulation) versus micronutrients depletion, are discussed in light of the conducted monitoring campaign. Although not completely elucidative, the complex, multifactorial process of leaf dust accumulation can better be understood through a combination of techniques.
Keywords: A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 5
DOI: 10.1016/J.ATMOSENV.2019.117082
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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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“In situ tailoring of superconducting junctions via electro-annealing”. Lombardo J, Jelić, ŽL, Baumans XDA, Scheerder JE, Nacenta JP, Moshchalkov VV, Van de Vondel J, Kramer RBG, Milošević, MV, Silhanek AV, Nanoscale 10, 1987 (2018). http://doi.org/10.1039/C7NR08571K
Abstract: We demonstrate the in situ engineering of superconducting nanocircuitry by targeted modulation of material properties through high applied current densities. We show that the sequential repetition of such customized electro-annealing in a niobium (Nb) nanoconstriction can broadly tune the superconducting critical temperature T-c and the normal-state resistance R-n in the targeted area. Once a sizable R-n is reached, clear magneto-resistance oscillations are detected along with a Fraunhofer-like field dependence of the critical current, indicating the formation of a weak link but with further adjustable characteristics. Advanced Ginzburg-Landau simulations fully corroborate this picture, employing the detailed parametrization from the electrical characterization and high resolution electron microscope images of the region within the constriction where the material has undergone amorphization by electro-annealing.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 7.367
Times cited: 23
DOI: 10.1039/C7NR08571K
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“An adhesive conducting electrode material based on commercial mesoporous titanium dioxide as a support for Horseradish peroxidase for bioelectrochemical applications”. Rahemi V, Trashin S, Meynen V, De Wael K, Talanta : the international journal of pure and applied analytical chemistry 146, 689 (2016). http://doi.org/10.1016/J.TALANTA.2015.06.041
Abstract: An adhesive conducting electrode material containing of graphite, biocompatible ion exchange polymer nafion® and commercial mesoporous TiO2 impregnated with horseradish peroxidase (HRP) is prepared and characterized by amperometric, UVvis and N2 sorption methods. The factors influencing the performance of the resulting biosensor are studied in detail. The optimal electrode material consists of 45% graphite, 50% impregnated HRPTiO2 and 5% nafion®. The optimum conditions for H2O2 reduction are an applied potential of 0.3 V and 0.1 mM hydroquinone. Sensitivity and limit of detection in the optimum conditions are 1 A M−1 cm−2 and 1 µM correspondingly. The N2 sorption results show that the pore volume of TiO2 decreases sharply upon adsorption of HRP. The preparation process of the proposed enzyme electrode is straightforward and potentially can be used for preparation of carbon paste electrodes for bioelectrochemical detections.
Keywords: A1 Journal article; Laboratory of adsorption and catalysis (LADCA); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 4.162
Times cited: 7
DOI: 10.1016/J.TALANTA.2015.06.041
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“Attaching redox proteins onto electrode surfaces by bis-silane”. Trashin S, De Jong M, Meynen V, Dewilde S, De Wael K, ChemElectroChem 3, 1035 (2016). http://doi.org/10.1002/CELC.201600021
Abstract: Immobilization of redox proteins on electrode surfaces is of special interest for mechanistic studies and applications because of a well-controlled redox state of protein molecules by a polarized electrode and fast electron transfer kinetics, free from diffusion limitation. Here, bis-organosilane (1,2-bis(trimethoxysilyl)ethane) was applied as a fresh solution in a pH 7 phosphate buffer without use of any organic solvent, sol-gel or mesoporous bulk matrix. A short aging period of 30 minutes before deposition on the electrodes was optimal for the immobilization of proteins. Three redox proteins (cytochrome c, neuroglobin and GLB-12) were confined to the gold surface of electrodes with high coverages and stability, indicating that the suggested technique is simple, efficient and generic in nature.
Keywords: A1 Journal article; Laboratory of adsorption and catalysis (LADCA); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 4.136
Times cited: 4
DOI: 10.1002/CELC.201600021
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“Evidence of tetragonal distortion as the origin of the ferromagnetic ground state in gamma-Fe nanoparticles”. Augustyns V, van Stiphout K, Joly V, Lima TAL, Lippertz G, Trekels M, Menendez E, Kremer F, Wahl U, Costa ARG, Correia JG, Banerjee D, Gunnlaugsson HP, von Bardeleben J, Vickridge I, Van Bael MJ, Hadermann J, Araujo JP, Temst K, Vantomme A, Pereira LMC, Physical review B 96, 174410 (2017). http://doi.org/10.1103/PHYSREVB.96.174410
Abstract: <script type='text/javascript'>document.write(unpmarked('gamma-Fe and related alloys are model systems of the coupling between structure and magnetism in solids. Since different electronic states (with different volumes and magnetic ordering states) are closely spaced in energy, small perturbations can alter which one is the actual ground state. Here, we demonstrate that the ferromagnetic state of gamma-Fe nanoparticles is associated with a tetragonal distortion of the fcc structure. Combining a wide range of complementary experimental techniques, including low-temperature Mossbauer spectroscopy, advanced transmission electron microscopy, and synchrotron radiation techniques, we unambiguously identify the tetragonally distorted ferromagnetic ground state, with lattice parameters a = 3.76(2) angstrom and c = 3.50(2) angstrom, and a magnetic moment of 2.45(5) mu(B) per Fe atom. Our findings indicate that the ferromagnetic order in nanostructured gamma-Fe is generally associated with a tetragonal distortion. This observation motivates a theoretical reassessment of the electronic structure of gamma-Fe taking tetragonal distortion into account.'));
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 1
DOI: 10.1103/PHYSREVB.96.174410
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“Study of the intrinsic limitations of the contact resistance of metal/semiconductor interfaces through atomistic simulations”. Dabral A, Pourtois G, Sankaran K, Magnus W, Yu H, de de Meux AJ, Lu AKA, Clima S, Stokbro K, Schaekers M, Collaert N, Horiguchi N, Houssa M, ECS journal of solid state science and technology 7, N73 (2018). http://doi.org/10.1149/2.0041806JSS
Abstract: In this contribution, we report a fundamental study of the factors that set the contact resistivity between metals and highly doped n-type 2D and 3D semiconductors. We investigate the case of n-type doped Si contacted with amorphous TiSi combining first principles calculations with Non-Equilibrium Green functions transport simulations. The evolution of the intrinsic contact resistivity with the doping concentration is found to saturate at similar to 2 x 10(-10) Omega.cm(2) for the case of TiSi and imposes an intrinsic limit to the ultimate contact resistance achievable for n-doped Silamorphous-TiSi (aTiSi). The limit arises from the intrinsic properties of the semiconductors and of the metals such as their electron effective masses and Fermi energies. We illustrate that, in this regime, contacting heavy electron effective mass metals with semiconductor helps reducing the interface intrinsic contact resistivity. This observation seems to hold true regardless of the 3D character of the semiconductor, as illustrated for the case of three 2D semiconducting materials, namely MoS2, ZrS2 and HfS2. (C) The Author(s) 2018. Published by ECS.
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 1.787
Times cited: 2
DOI: 10.1149/2.0041806JSS
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“Macroscopic X-ray powder diffraction scanning, a new method for highly selective chemical imaging of works of art : instrument optimization”. Vanmeert F, de Nolf W, De Meyer S, Dik J, Janssens K, Analytical chemistry 90, 6436 (2018). http://doi.org/10.1021/ACS.ANALCHEM.8B00240
Abstract: In the past decade macroscopic X-ray fluorescence imaging (MA-XRF) has become established as a method for the noninvasive investigation of flat painted surfaces, yielding large scale elemental maps. MA-XRF is limited by a lack of specificity, only allowing for indirect pigment identification based on the simultaneous presence of chemical elements. The high specificity of X-ray powder diffraction (XRPD) mapping is already being exploited at synchrotron facilities for investigations at the (sub)microscopic scale, but the technique has not yet been employed using lab sources. In this paper we present the development of a novel MA-XRPD/XRF instrument based on a laboratory X-ray source. Several combinations of X-ray sources and area detectors are evaluated in terms of their spatial and angular resolution and their sensitivity. The highly specific imaging capability of the combined MA-XRPD/XRF instrument is demonstrated on a 15th/16th century illuminated manuscript directly revealing the distribution of a large number of inorganic pigments, including the uncommon yellow pigment massicot (o-PbO). The case study illustrates the wealth of new mapping information that can be obtained in a noninvasive manner using the laboratory MA-XRPD/XRF instrument.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 6.32
Times cited: 11
DOI: 10.1021/ACS.ANALCHEM.8B00240
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“Toward unlocking the Mn3+/Mn2+ redox pair in alluaudite-type Na2+2zMn2-z(SO4)3-x(SeO4)x cathodes for sodium-ion batteries”. Kirsanova MA, De Sloovere D, Karakulina OM, Hadermann J, Van Bael MK, Hardy A, Abakumov AM, Journal of solid state chemistry 277, 804 (2019). http://doi.org/10.1016/J.JSSC.2019.07.032
Abstract: In polyanion cathodes, the inductive effect alters the potential of a M(n+1)+/Mn+ redox couple (M – transition metal) according to the electronegativity of the X cation in the polyanion groups (XO4m+). To manipulate the operating potential, we synthesized a series of mixed sulfate-selenate alluaudites, with structure formulas Na2+2zMn2-z(SO4)(3-x)(SeO4)(x) and Na2.81Ni1.60(SO4)(1.43)(SeO4)(1.57). Their crystal structure was determined from powder X-ray diffraction data, revealing that the Mn-based alluaudites form solid solutions with the same crystal structure for x = 0.75; 1.125 and 1.5. Na2.81Ni1.60(SO4)(1.43)(SeO4)(1.57) is isostructural to the Mn-based alluaudites. Although the Na2+2zMn2-z(SO4)(3-x)(SeO4)(x) compound with the highest selenium content demonstrates a reversible discharge capacity of 60 mAh g(-1), only a small part of this electrochemical activity can be ascribed to the Mn3+/Mn2+ redox couple. The redox potential of the Mn3+/Mn2+ pair in Na2+2zMn2-z(SO4)(3-)x(SeO4)(x) decreases with increasing values of x, in agreement with the lower electronegativity of Se compared to that of S.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.299
DOI: 10.1016/J.JSSC.2019.07.032
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“Role of coating-metallic support interaction in the properties of electrosynthesized Rh-based structured catalysts”. Benito P, de Nolf W, Nuyts G, Janssens K, et al, ACS catalysis 4, 3779 (2014). http://doi.org/10.1021/CS501079K
Abstract: Rh-structured catalysts for the catalytic partial oxidation of CH4 to syngas were prepared by electrosynthesis of Rh-containing hydrotalcite-type (HT) compounds on FeCrAlloy foams followed by calcination at 900 degrees C. During the calcination the simultaneous decomposition of the layered HT structure and formation of the protective FeCrAlloy outer shell in alumina occurred. Here, we studied the role of the coating-metallic support interaction in the properties of the catalysts after calcination, H-2 reduction, and catalytic tests, by a combination of electron (FEG-SEM/EDS) and synchrotron X-ray (XRF/XRPD and XRF/XANES) microscopic techniques. The characterization of crystalline phases in the metallic support and coating and distribution of Rh active species was carried out on several samples prepared by modifying the Rh content in the electrolytic solution (Rh/Mg/Al = 11.0/70.0/19.0, 5.0/70.0/25.0, 0/70.0/30.0 atomic ratio). A sample was also prepared with no aluminum in the electrolytic solution (Rh/Mg/Al = 13.6/86.4/0.0 atomic ratio) and calcined at 550 and 900 degrees C. The interaction between the elements of the metallic support and the catalytic coating increased the film adhesion during the thermal treatment and catalytic tests and modified the catalyst crystalline phases. A chemical reaction between Al corning from the foam and Mg in the coating occurred during calcination at high temperature leading to the formation of spinel phases in which rhodium is solved, together with some Rh2O3 and Rh. The metallic support was oxidized forming the corundum scale and chromium oxides, moreover t-Al2O3 was identified. For the Rh11.0Mg70.0Al19.0 catalyst the inclusion of Rh in the spinel phase decreased its reducibility in the H-2 pretreatment. The reduction continued during catalytic tests by feeding diluted CH4/O-2/He gas mixtures, evidenced by the catalyst activation. While under concentrated gas mixtures the deactivation occurred, probably by oxidation.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 10.614
Times cited: 13
DOI: 10.1021/CS501079K
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“Diluted oxide interfaces with tunable ground states”. Gan Y, Christensen DV, Zhang Y, Zhang H, Krishnan D, Zhong Z, Niu W, Carrad DJ, Norrman K, von Soosten M, Jespersen TS, Shen B, Gauquelin N, Verbeeck J, Sun J, Pryds N, Chen Y, Advanced materials 31, 1805970 (2019). http://doi.org/10.1002/ADMA.201805970
Abstract: The metallic interface between two oxide insulators, such as LaAlO3/SrTiO3 (LAO/STO), provides new opportunities for electronics and spintronics. However, due to the presence of multiple orbital populations, tailoring the interfacial properties such as the ground state and metal-insulator transitions remains challenging. Here, an unforeseen tunability of the phase diagram of LAO/STO is reported by alloying LAO with a ferromagnetic LaMnO3 insulator without forming lattice disorder and at the same time without changing the polarity of the system. By increasing the Mn-doping level, x, of LaAl1-xMnxO3/STO (0 <= x <= 1), the interface undergoes a Lifshitz transition at x = 0.225 across a critical carrier density of n(c) = 2.8 x 10(13) cm(-2), where a peak T-SC approximate to 255 mK of superconducting transition temperature is observed. Moreover, the LaAl1-xMnxO3 turns ferromagnetic at x >= 0.25. Remarkably, at x = 0.3, where the metallic interface is populated by only d(xy) electrons and just before it becomes insulating, a same device with both signatures of superconductivity and clear anomalous Hall effect (7.6 x 10(12) cm(-2) < n(s) <= 1.1 x 10(13) cm(-2)) is achieved reproducibly. This provides a unique and effective way to tailor oxide interfaces for designing on-demand electronic and spintronic devices.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 19.791
Times cited: 31
DOI: 10.1002/ADMA.201805970
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