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“On the nature of ferromagnetism in diluted magnetic semiconductors : GaAs:Mn”. Krstajic PM, Ivanov VA, Peeters FM, Fleurov V, Kikoin K, Europhysics letters 61, 235 (2003). http://doi.org/10.1209/epl/i2003-00224-x
Abstract: An energy level diagram is constructed on the basis of a microscopic Hamiltonian proposed for a description of interacting manganese impurities in diluted magnetic semiconductors (DMS). It is shown that ferromagnetism in p-type III-V DMS is governed by the strong hybridization of Mn2+-electrons with the mobile holes and localized states near the top of the valence band. The Curie temperature estimated from the proposed kinematic exchange agrees with the experiments on GaAs:Mn. The model is also applicable to the GaP:Mn system.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.957
Times cited: 38
DOI: 10.1209/epl/i2003-00224-x
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“Interface for reproducible, multishot direct analysis of solid-phase microextraction samples”. Newsome GA, Kavich G, Alvarez-Martin A, Analytical Chemistry 92, 4182 (2020). http://doi.org/10.1021/ACS.ANALCHEM.9B05691
Abstract: An enclosed interface that joins a direct analysis in real time (DART) probe, solid-phase microextraction (SPME) fiber, and the inlet of a high-resolution mass spectrometer is described. Unlike other systems to couple SPME sampling to ambient mass spectrometry, the interface is able to perform discrete analyses on different areas of a single SPME fiber device for up to three technical replicate measurements of one sampling event. Inlet flow speed and desorption temperature are optimized, and reproducibility is demonstrated between replicate analyses on the same derivatized SPME fiber and with sequential fiber sampling events, yielding analyte measurement center of variance (CV) from 3 to 6%. Conditioning is also performed with the enclosed DART. The interface is a straightforward addition to commercially available technologies, and machine diagrams for custom components operated with SPME/DART/MS equipment are included.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 7.4
DOI: 10.1021/ACS.ANALCHEM.9B05691
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“In situ high resolution electron microscopy observation of electron-irradiation-induced martensitic transformation in a Ni63Al37 alloy”. Muto S, Schryvers D, Journal of alloys and compounds 199, 1 (1993). http://doi.org/10.1016/0925-8388(93)90422-J
Abstract: An electron-irradiation-induced transformation from cubic beta2 austenite to monoclinic 7M martensite was observed in situ under high resolution electron microscopy conditions in a thin foil of Ni63Al37 beta2 phase (B2, CsCl structure), with the start temperature of the martensitic transformation below but very close to room temperature. The structure of the martensite is consistent with thermoelastic or stress-induced martensite at this composition, including the existence of multiple stacking faults. The transformation is described by a gradual increase in the shear and shuffle amplitudes already existing in the precursor domains. Possible origins of the transformation are discussed.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 2.999
Times cited: 8
DOI: 10.1016/0925-8388(93)90422-J
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“A biosensor fabricated by incorporation of a redox mediator into a carbon nanotube/nafion composite for tyrosinase immobilization : detection of matairesinol, an endocrine disruptor”. Rather JA, Pilehvar S, De Wael K, The analyst 238, 204 (2013). http://doi.org/10.1039/C2AN35959F
Abstract: An electrochemical matairesinol biosensor was fabricated by immobilizing tyrosinase on a poly(thionine)/nafion/multi-walled carbon nanotube composite film. A polymeric film of the redox dye thionine enables the stable immobilization of tyrosinase while acting as a mediator for the enzymatic process has been incorporated into the carbon nanotube/nafion composite film. The immobilization method is based on crosslinking of the tyrosinase layer with an electropolymerized film of poly(thionine). The good homogenization of the electron conductor CNTs in the integrated films provides the possibility of a three-dimensional electron conductive network. The biosensor was characterized by electrochemical impedance spectroscopy and electrochemical characterization. The composite electrode exhibits catalytic activity, high sensitivity, stability and is applicable over a wide range of concentrations from 180 nM to 4.33 μM with a detection limit (LOD) of 37 nM. The obtained results suggest that the developed sensor can be successfully used for the determination of phenolic endocrine disruptors over a concentration range covering their environmental levels.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 3.885
Times cited: 23
DOI: 10.1039/C2AN35959F
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“Mixed hemi/ad-micelles coated magnetic nanoparticles for the entrapment of hemoglobin at the surface of a screen-printed carbon electrode and its direct electrochemistry and electrocatalysis”. Amiri-Aref M, Raoof JB, Kiekens F, De Wael K, Biosensors and bioelectronics 74, 518 (2015). http://doi.org/10.1016/J.BIOS.2015.07.001
Abstract: An efficient procedure for the physical entrapment of proteins within a biocompatible matrix and their immobilization on electrode surfaces is of utmost importance in the fabrication of biosensors. In this work, the magnetic entrapment of hemoglobin (Hb) at the surface of a screen-printed carbon electrode (SPCE), through mixed hemi/ad-micelles (MHAM) array of positively charged surfactant supported iron oxide magnetic nanoparticles (Mag-NPs), is reported. The Hb/MHAM@Mag-NPs biocomposite is captured at SPCE by a super magnet (Hb/MHAM@Mag-NPs/SPCE). To gain insight in the configuration of the mixed hemi/ad-micelles of CTAB at Mag-NPs, zeta-potential measurements were performed. The entrapment of Hb at MHAM@Mag-NPs was confirmed by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Fourier transform infrared spectroscopy (FT-IR). Direct electron transfer of the Hb intercalated into the composite film showed a pair of well-defined quasi-reversible redox peak at formal potential of −0.255 V vs. Ag/AgCl corresponding to heme Fe(III)/Fe(II) redox couple. It shows that the MHAM@Mag-NPs composite could increase the adsorption ability for Hb, thus provides a facile direct electron transfer between the Hb and the substrate. The proposed biosensor showed excellent electrocatalytic activity to the H2O2 reduction in the wide concentration range from 5.0 to 300.0 µM obtained by amperometric measurement. The MichaelisMenten constant (Km) value of Hb at the modified electrode is 55.4 µM, showing its high affinity. Magnetic entrapment offers a promising design for fast, convenient and effective immobilization of protein within a few minutes for determination of the target molecule in low sample volume at disposable cost-effective SPCE.
Keywords: A1 Journal article; Pharmacology. Therapy; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 7.78
Times cited: 14
DOI: 10.1016/J.BIOS.2015.07.001
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“An accurate parameterization for scattering factors, electron densities and electrostatic potentials for neutral atoms that obey all physical constraints”. Lobato Hoyos IP, van Dyck D, Acta crystallographica: section A: foundations of crystallography 70, 636 (2014). http://doi.org/10.1107/S205327331401643X
Abstract: An efficient procedure and computer program are outlined for fitting numerical X-ray and electron scattering factors with the correct inclusion of all physical constraints. The numerical electron scattering factors have been parameterized using five analytic non-relativistic hydrogen electron scattering factors as basis functions for 103 neutral atoms of the periodic table. The inclusion of the correct physical constraints in the electron scattering factor and its derived quantities allows the use of the new parameterization in different fields. In terms of quality of the fit, the proposed parameterization of the electron scattering factor is one order of magnitude better than the previous analytic fittings.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 5.725
Times cited: 19
DOI: 10.1107/S205327331401643X
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“Efficient fitting algorithm”. de Backer A, Fatermans J, den Dekker AJ, Van Aert S Advances in imaging and electron physics
T2 – Advances in imaging and electron physics. page 73 (2021).
Abstract: An efficient model-based estimation algorithm is introduced to quantify the atomic column positions and intensities from atomic-resolution (scanning) transmission electron microscopy ((S)TEM) images. This algorithm uses the least squares estimator on image segments containing individual columns fully accounting for overlap between neighboring columns, enabling the analysis of a large field of view. To provide end-users with this well-established quantification method, a user friendly program, StatSTEM, is developed which is freely available under a GNU public license. In this chapter, this efficient algorithm is applied to three different nanostructures for which the analysis of a large field of view is required.
Keywords: H2 Book chapter; Electron microscopy for materials research (EMAT)
DOI: 10.1016/BS.AIEP.2021.01.003
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“StatSTEM: An efficient program for accurate and precise model-based quantification of atomic resolution electron microscopy images”. De Backer A, van den Bos KHW, Van den Broek W, Sijbers J, Van Aert S, Journal of physics : conference series
T2 –, Electron Microscopy and Analysis Group Conference 2017 (EMAG2017), 3-6 July 2017, Manchester, UK 902, 012013 (2017). http://doi.org/10.1088/1742-6596/902/1/012013
Abstract: An efficient model-based estimation algorithm is introduced in order to quantify the atomic column positions and intensities from atomic resolution (scanning) transmission electron microscopy ((S)TEM) images. This algorithm uses the least squares estimator on image segments containing individual columns fully accounting for the overlap between neighbouring columns, enabling the analysis of a large field of view. For this algorithm, the accuracy and precision with which measurements for the atomic column positions and scattering cross-sections from annular dark field (ADF) STEM images can be estimated, is investigated. The highest attainable precision is reached even for low dose images. Furthermore, advantages of the model- based approach taking into account overlap between neighbouring columns are highlighted. To provide end-users this well-established quantification method, a user friendly program, StatSTEM, is developed which is freely available under a GNU public license.
Keywords: P1 Proceeding; Electron microscopy for materials research (EMAT); Vision lab
Times cited: 1
DOI: 10.1088/1742-6596/902/1/012013
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“Nitrogen and luminescent nitrogen-vacancy defects in detonation nanodiamond”. Vlasov II, Shenderova O, Turner S, Lebedev OI, Basov AA, Sildos I, Rähn M, Shiryaev AA, Van Tendeloo G, Small 6, 687 (2010). http://doi.org/10.1002/smll.200901587
Abstract: An efficient method to investigate the microstructure and spatial distribution of nitrogen and nitrogen-vacancy (N-V) defects in detonation nanodiamond (DND) with primary particle sizes ranging from approximately 3 to 50 nm is presented. Detailed analysis reveals atomic nitrogen concentrations as high as 3 at% in 50% of diamond primary particles with sizes smaller than 6 nm. A non-uniform distribution of nitrogen within larger primary DND particles is also presented, indicating a preference for location within the defective central part or at twin boundaries. A photoluminescence (PL) spectrum with well-pronounced zero-phonon lines related to the N-V centers is demonstrated for the first time for electron-irradiated and annealed DND particles at continuous laser excitation. Combined Raman and PL analysis of DND crystallites dispersed on a Si substrate leads to the conclusion that the observed N-V luminescence originates from primary particles with sizes exceeding 30 nm. These findings demonstrate that by manipulation of the size/nitrogen content in DND there are prospects for mass production of nanodiamond photoemitters based on bright and stable luminescence from nitrogen-related defects.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 8.643
Times cited: 84
DOI: 10.1002/smll.200901587
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“C2-H arylation of indoles catalyzed by palladium-containing metal-organic-framework in γ-valerolactone”. Anastasiou I, Van Velthoven N, Tomarelli E, Lombi A, Lanari D, Liu P, Bals S, De Vos DE, Vaccaro L, Chemsuschem 13 (2020). http://doi.org/10.1002/CSSC.202000378
Abstract: An efficient and selective procedure was developed for the direct C2-H arylation of indoles using a Pd-loaded metal-organic framework (MOF) as a heterogeneous catalyst and the nontoxic biomass-derived solvent gamma-valerolactone (GVL) as a reaction medium. The developed method allows for excellent yields and C-2 selectivity to be achieved and tolerates various substituents on the indole scaffold. The established conditions ensure the stability of the catalyst as well as recoverability, reusability, and low metal leaching into the solution.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 8.4
Times cited: 22
DOI: 10.1002/CSSC.202000378
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“Conductance fluctuations of monolayer GeSnH2$ in the topological phase using a low-energy effective tight-binding Hamiltonian”. Aslani Z, Sisakht ET, Fazileh F, Ghorbanfekr-Kalashami H, Peeters FM, Physical review B 99, 115421 (2019). http://doi.org/10.1103/PHYSREVB.99.115421
Abstract: An effective tight-binding (TB) Hamiltonian for monolayer GeSnH2 is constructed which has an inversion-asymmetric honeycomb structure. The low-energy band structure of our TB model agrees very well with previous ab initio calculations even under biaxial tensile strain. Our model predicts a phase transition at 7.5% biaxial tensile strain in agreement with DFT calculations. Upon 8.5% strain the system exhibits a band gap of 134 meV, suitable for room temperature applications. It is shown that an external applied magnetic field produces a special phase which is a combination of the quantum Hall (QH) and quantum spin Hall (QSH) phases; and at a critical magnetic field strength the QSH phase completely disappears. The topological nature of the phase transition is confirmed from: (1) the calculation of the Z(2) topological invariant, and (2) quantum transport properties of disordered GeSnH2 nanoribbons which allows us to determine the universality class of the conductance fluctuations. The application of an external applied magnetic field reduces the conductance fluctuations by a factor of root 2.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 3
DOI: 10.1103/PHYSREVB.99.115421
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“StatSTEM: An efficient approach for accurate and precise model-based quantification of atomic resolution electron microscopy images”. De Backer A, van den Bos KHW, Van den Broek W, Sijbers J, Van Aert S, Ultramicroscopy 171, 104 (2016). http://doi.org/10.1016/j.ultramic.2016.08.018
Abstract: An efficient model-based estimation algorithm is introduced to quantify the atomic column positions and intensities from atomic resolution (scanning) transmission electron microscopy ((S)TEM) images. This algorithm uses the least squares estimator on image segments containing individual columns fully accounting for overlap between neighbouring columns, enabling the analysis of a large field of view. For this algorithm, the accuracy and precision with which measurements for the atomic column positions and scattering cross-sections from annular dark field (ADF) STEM images can be estimated, has been investigated. The highest attainable precision is reached even for low dose images. Furthermore, the advantages of the model-based approach taking into account overlap between neighbouring columns are highlighted. This is done for the estimation of the distance between two neighbouring columns as a function of their distance and for the estimation of the scattering cross-section which is compared to the integrated intensity from a Voronoi cell. To provide end-users this well-established quantification method, a user friendly program, StatSTEM, is developed which is freely available under a GNU public license.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 2.843
Times cited: 43
DOI: 10.1016/j.ultramic.2016.08.018
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“Automated quantitative electron-microprobe analysis of particulate material”. Van Dyck P, Storms H, Van Grieken R, Journal de physique 45, 781 (1984). http://doi.org/10.1051/JPHYSCOL:19842179
Abstract: An automated electron microprobe, equipped with an energy-dispersive X-ray spectrometer and an additional backscattered electron signal digitalization system, can allow rapid sizing and major element analysis on numerous particles. A software package has been developed to exploit the particle size and shape information to achieve quantitative analysis of single particles, and to compare the performance of the different matrix correction procedures.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1051/JPHYSCOL:19842179
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“Unique nanostructural features in Fe, Mn-doped YBCO thin films”. Meledin A, Turner S, Cayado P, Mundet B, Solano E, Ricart S, Ros J, Puig T, Obradors X, Van Tendeloo G, Superconductor science and technology 29, 125009 (2016). http://doi.org/10.1088/0953-2048/29/12/125009
Abstract: An attempt to grow a thin epitaxial composite film of YBa2Cu3O7−δ (YBCO) with spinel MnFe2O4 (MFO) nanoparticles on a LAO substrate using the CSD approach resulted in a decomposition of the spinel and various doping modes of YBCO with the Fe and Mn cations. These nanostructural effects lead to a lowering of T c and a slight J c increase in field. Using a combination of advanced transmission electron microscopy (TEM) techniques such as atomic resolution high-angle annular dark field scanning TEM, energy dispersive x-ray spectroscopy and electron energy-loss spectroscopy we have been able to decipher and characterize the effects of the Fe and Mn doping on the film architecture. The YBaCuFeO5 anion-deficient double perovskite phase was detected in the form of 3D inclusions as well as epitaxially grown lamellas within the YBCO matrix. These nano-inclusions play a positive role as pinning centers responsible for the J c/J sf (H) dependency smoothening at high magnetic fields in the YBCO-MFO films with respect to the pristine YBCO films.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.878
Times cited: 6
DOI: 10.1088/0953-2048/29/12/125009
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“Aqueous solubility calculation for petroleum mixtures in soil using comprehensive two-dimensional gas chromatography analysis data”. Mao D, Lookman R, van de Weghe H, Vanermen G, de Brucker N, Diels L, Journal of chromatography : A 1216, 2873 (2009). http://doi.org/10.1016/J.CHROMA.2008.08.072
Abstract: An assessment of aqueous solubility (leaching potential) of soil contaminations with petroleum hydrocarbons (TPH) is important in the context of the evaluation of (migration) risks and soil/groundwater remediation. Field measurements using monitoring wells often overestimate real TPH concentrations in case of presence of pure oil in the screened interval of the well. This paper presents a method to calculate TPH equilibrium concentrations in groundwater using soil analysis by high-performance liquid chromatography followed by comprehensive two-dimensional gas chromatography (HPLCGCXGC). The oil in the soil sample is divided into 79 defined hydrocarbon fractions on two GCXGC color plots. To each of these fractions a representative water solubility is assigned. Overall equilibrium water solubility of the non-aqueous phase liquid (NAPL) present in the sample and the water phase's chemical composition (in terms of the 79 fractions defined) are then calculated using Raoult's law. The calculation method was validated using soil spiked with 13 different TPH mixtures and 1 field-contaminated soil. Measured water solubilities using a column recirculation equilibration experiment agreed well to calculated equilibrium concentrations and water phase TPH composition.
Keywords: A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1016/J.CHROMA.2008.08.072
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“Networks of quantum nanorings : programmable spintronic devices”. Földi P, Kálmán O, Benedict MG, Peeters FM, Nano letters 8, 2556 (2008). http://doi.org/10.1021/nl801858a
Abstract: An array of quantum rings with local (ring by ring) modulation of the spin orbit interaction (SOI) can lead to novel effects in spin state transformation of electrons. It is shown that already small (3 x 3, 5 x 5) networks are remarkably versatile from this point of view: Working in a given network geometry, the input current can be directed to any of the output ports, simply by changing the SOI strengths by external gate voltages. Additionally, the same network with different SOI strengths can be completely analogous to the Stern-Gerlach device, exhibiting spatial-spin entanglement.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 12.712
Times cited: 76
DOI: 10.1021/nl801858a
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“Understanding Microwave Surface-Wave Sustained Plasmas at Intermediate Pressure by 2D Modeling and Experiments: Understanding Microwave Surface-Wave Sustained Plasmas …”. Georgieva V, Berthelot A, Silva T, Kolev S, Graef W, Britun N, Chen G, van der Mullen J, Godfroid T, Mihailova D, van Dijk J, Snyders R, Bogaerts A, Delplancke-Ogletree M-P, Plasma processes and polymers 14, 1600185 (2017). http://doi.org/10.1002/ppap.201600185
Abstract: An Ar plasma sustained by a surfaguide wave launcher is investigated at intermediate pressure (200–2667 Pa). Two 2D self-consistent models (quasi-neutral and plasma bulk-sheath) are developed and benchmarked. The complete set of electromagnetic and fluid equations and the boundary conditions are presented. The transformation of fluid equations from a local reference frame, that is, moving with plasma or when the gas flow is zero, to a laboratory reference frame, that is,
accounting for the gas flow, is discussed. The pressure range is extended down to 80 Pa by experimental measurements. The electron temperature decreases with pressure. The electron density depends linearly on power, and changes its behavior with pressure depending on the product of pressure and radial plasma size.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.846
Times cited: 8
DOI: 10.1002/ppap.201600185
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“The use of lead dodecanoate as an environmentally friendly coating to inhibit the corrosion of lead objects : comparison of three different deposition methods”. De Keersmaecker M, De Wael K, Adriaens A, Progress in organic coatings 74, 1 (2012). http://doi.org/10.1016/J.PORGCOAT.2012.01.014
Abstract: An aqueous sodium dodecanoate solution has been used for the formation of a protective coating for lead. Three deposition methods have been compared: immobilization using cyclic voltammetry, immersion and amperometry. Apart from this, we tested a reduction pretreatment of the lead surface (−1.5 V during 600 s) in order to obtain a more reproducible coating, resulting in a better corrosion protection behavior. The corrosion inhibition properties were examined using potentiodynamic polarization curves and electrochemical impedance measurements in a standard corrosive environment.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 2.858
Times cited: 8
DOI: 10.1016/J.PORGCOAT.2012.01.014
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Blust RJP, Dardenne F, De Wael K, Nagels L, Van Camp G (2013) Electrochemical aptasensors with a gelatin B matrix : EP13175128
Abstract: An aptamer-based electrochemical sensor, wherein said aptamer is covalently bonded to or chemisorbed on an electrode, said aptamer forming a robust complex with a target molecule and is encapsulated by a gelatin B matrix; a method of manufacturing an aptamer-based electrochemical sensor for determining a concentration of a target molecule comprising the steps of: selecting an aptamer to form a robust complex with a target molecule using the SELEX procedure; synthesizing said aptamer; adsorbing said aptamer on or covalently coupling said aptamer with an electrode; and providing a gelatin B matrix for said aptamer on said electrode thereby realising said aptamer-based potentiometric or amperometric sensor; and the use of the aptamer-based electrochemical sensor produced according to the above method for the electrochemical determination of a concentration of 15 the target molecule.
Keywords: Patent; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
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“Monte Carlo simulation of X-ray spectra from low energy electrons using optical data”. Roet D, van Espen P, Nuclear instruments and methods in physics research: B: beam interactions with materials and atoms 268, 2794 (2010). http://doi.org/10.1016/J.NIMB.2010.07.004
Abstract: An approach using optical data to simulate both the bremsstrahlung continuum and characteristic K and L X-ray lines generated by low energy electrons (cfr. electron microscopy) in solids is discussed in this paper. The necessary analytical expressions together with the data to calculate the relevant cross sections for elastic and inelastic interactions at these energies along with variance reduction techniques are given. The results of the Monte Carlo simulation are compared to experimental data measured with a JEOL 6300 electron microscope.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/J.NIMB.2010.07.004
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“Spectroscopy of snake states using a graphene Hall bar”. Milovanović, SP, Masir MR, Peeters FM, Applied physics letters 103, 233502 (2013). http://doi.org/10.1063/1.4838557
Abstract: An approach to observe snake states in a graphene Hall bar containing a pn-junction is proposed. The magnetic field dependence of the bend resistance in a ballistic graphene Hall bar structure containing a tilted pn-junction oscillates as a function of applied magnetic field. We show that each oscillation is due to a specific snake state that moves along the pn-interface. Furthermore, depending on the value of the magnetic field and applied potential, we can control the lead in which the electrons will end up and hence control the response of the system.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 15
DOI: 10.1063/1.4838557
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“Electronic and optical properties of a circular graphene quantum dot in a magnetic field : influence of the boundary conditions”. Grujić, M, Zarenia M, Chaves A, Tadić, M, Farias GA, Peeters FM, Physical review : B : condensed matter and materials physics 84, 205441 (2011). http://doi.org/10.1103/PhysRevB.84.205441
Abstract: An analytical approach, using the Dirac-Weyl equation, is implemented to obtain the energy spectrum and optical absorption of a circular graphene quantum dot in the presence of an external magnetic field. Results are obtained for the infinite-massand zigzag boundary conditions. We found that the energy spectrum of a dot with the zigzag boundary condition exhibits a zero-energy band regardless of the value of the magnetic field, while for the infinite-mass boundary condition, the zero-energy states appear only for high magnetic fields. The analytical results are compared to those obtained from the tight-binding model: (i) we show the validity range of the continuum model and (ii) we find that the continuum model with the infinite-mass boundary condition describes rather well its tight-binding analog, which can be partially attributed to the blurring of the mixed edges by the staggered potential.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 78
DOI: 10.1103/PhysRevB.84.205441
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“A counterion-catalyzed (S0H+)(X-I+) pathway toward heat- and steam-stable mesostructured silica assembled from amines in acidic conditions”. Cassiers K, van der Voort P, Linssen T, Vansant EF, Lebedev O, van Landuyt J, The journal of physical chemistry : B : condensed matter, materials, surfaces, interfaces and biophysical 107, 3690 (2003). http://doi.org/10.1021/jp026696v
Abstract: An alternative pathway to assemble mesoporous molecular sieve silicas is developed using nonionic alkylamines and N,N-dimethylalkylamines (SO) as structure-directing agents in acidic conditions. The synthesized mesostructures possess wormhole-like frameworks with pore sizes and pore volumes in the range of 20-90 Angstrom and 0.5-1.3 cm(3)/g, respectively. The formation of the mesophase is controlled by a counterion-mediated mechanism of the type (S(0)H(+))(X(-)I(+)), where S(0)H(+) are protonated water molecules that are hydrogen bonded to the lone electron pairs on the amine surfactant headgroups (S(0)H(+)), X(-) is the counteranion originating from the acid, and I(+) are the positively charged (protonated) silicate species. We found that the stronger the ion X(-) is bonded to S(0)H(+), the more it catalyzes the silica condensation into (S(0)H(+))(X(-)I(+)). Br(-) is shown to be a strong binding anion and therefore a fast silica polymerization promoter compared to Cl(-) resulting in the formation of a higher quality mesophase for the Br(-) syntheses. We also showed that the polymerization rate of the silica, dictated by the counterion, controls the morphology of the mesostructures from nonuniform agglomerated blocks in the case of Br(-) syntheses to spherical particles for the Cl(-) syntheses. Next to many benefits such as low temperature, short synthesis time, and the use of inexpensive, nontoxic, and easily extractable amine templates, the developed materials have a remarkable higher thermal and hydrothermal stability compared to hexagonal mesoporous silica, which is also prepared with nonionic amines but formed through the S(0)I(0) mechanism.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Laboratory of adsorption and catalysis (LADCA)
Impact Factor: 3.177
Times cited: 9
DOI: 10.1021/jp026696v
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“Optimal sample preparation to characterize corrosion in historical photographs with analytical TEM”. Grieten E, Caen J, Schryvers D, Microscopy and microanalysis 20, 1585 (2014). http://doi.org/10.1017/S1431927614012860
Abstract: An alternative focused ion beam preparation method is used for sampling historical photographs containing metallic nanoparticles in a polymer matrix. We use the preparation steps of classical ultra-microtomy with an alternative final sectioning with a focused ion beam. Transmission electron microscopy techniques show that the lamella has a uniform thickness, which is an important factor for analytical transmission electron microscopy. Furthermore, the method maintains the spatial distribution of nanoparticles in the soft matrix. The results are compared with traditional preparation techniques such as ultra-microtomy and classical focused ion beam milling.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Antwerp Cultural Heritage Sciences (ARCHES)
Impact Factor: 1.891
DOI: 10.1017/S1431927614012860
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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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“Detection of amyloid fibrils in Parkinson’s disease using plasmonic chirality”. Kumar J, Eraña H, López-Martínez E, Claes N, Martín VF, Solís DM, Bals S, Cortajarena AL, Castilla J, Liz-Marzán LM, Proceedings of the National Academy of Sciences of the United States of America 115, 3225 (2018). http://doi.org/10.1073/pnas.1721690115
Abstract: Amyloid fibrils, which are closely associated with various neurodegenerative
diseases, are the final products in many protein aggregation pathways. The identification of fibrils at low concentration is, therefore, pivotal in disease diagnosis and development of therapeutic strategies. We report a methodology for the specific identification of amyloid fibrils using chiroptical effects in plasmonic nanoparticles. The formation of amyloid fibrils based on α-synuclein was probed using gold nanorods, which showed no
apparent interaction with monomeric proteins but effective adsorption onto fibril structures via noncovalent interactions. The amyloid structure drives a helical nanorod arrangement, resulting in intense optical activity at the surface plasmon resonance wavelengths. This sensing technique was successfully applied to human brain homogenates of patients affected by Parkinson’s disease,
wherein protein fibrils related to the disease were identified through chiral signals from Au nanorods in the visible and near IR, whereas healthy brain samples did not exhibit any meaningful optical activity. The technique was additionally extended to the specific detection of infectious amyloids formed by prion proteins, thereby confirming the wide potential of the technique. The intense chiral response driven by strong dipolar coupling in helical Au nanorod arrangements allowed us to detect amyloid fibrils down to nanomolar concentrations.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 9.661
Times cited: 187
DOI: 10.1073/pnas.1721690115
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“Derivatization of amphetamine to allow its electrochemical detection in illicit drug seizures”. Parrilla M, Montiel FN, Van Durme F, De Wael K, Sensors And Actuators B-Chemical 337, 129819 (2021). http://doi.org/10.1016/J.SNB.2021.129819
Abstract: Amphetamine (AMP) is posing critical issues in our society being one of the most encountered drugs-of-abuse in the current illicit market. The continuous drug production in Europe urges the development of new tools for the rapid on-site determination of illicit drugs such as AMP. However, the direct electrochemical detection of AMP is a challenge because the molecule is non-electroactive at the potential window of conventional graphite SPEs. For this reason, a derivatization step is needed to convert the primary amine into an electroactive oxidizable group. Herein, the rapid electrochemical detection of AMP in seized samples based on the derivatization by 1,2-naphthoquinone-4-sulfonate (NQS) is presented by using square wave voltammetry (SWV) at graphite screen-printed electrodes (SPEs). First, a detailed optimization of the key parameters and the analytical performance is provided. The method showed a sensitivity of 7.9 µA mM-1 within a linear range from 50 to 500 µM, a limit of detection of 22.2 µM, and excellent reproducibility (RSD = 4.3%, n = 5 at 500 µM). Subsequently, the effect of NQS on common cutting agents for the selective detection of AMP is addressed. The comparison of the method with drugs-of-abuse containing secondary and tertiary amines confirms the selectivity of the method. Finally, the concept is applied to quantify AMP in 20 seized samples provided by forensic laboratories, exhibiting an accuracy of 97.3 ± 10.5%. Overall, the fast analysis of samples with the electrochemical profiling of derivatized AMP exhibits a straightforward on-site screening aiming to facilitate the tasks of law enforcement agents in the field.
Keywords: A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 5.401
DOI: 10.1016/J.SNB.2021.129819
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“Synthesis of uniformly dispersed anatase nanoparticles inside mesoporous silica thin films via controlled breakup and crystallization of amorphous TiO2 deposited using atomic layer deposition”. Sree SP, Dendooven J, Masschaele K, Hamed HM, Deng S, Bals S, Detavernier C, Martens JA, Nanoscale 5, 5001 (2013). http://doi.org/10.1039/c3nr00594a
Abstract: Amorphous titanium dioxide was introduced into the pores of mesoporous silica thin films with 75% porosity and 12 nm average pore diameter via Atomic Layer Deposition (ALD) using alternating pulses of tetrakis(dimethylamino)titanium and water. Calcination provoked fragmentation of the deposited amorphous TiO2 phase and its crystallization into anatase nanoparticles inside the nanoporous film. The narrow particle size distribution of 4 ± 2 nm and the uniform dispersion of the particles over the mesoporous silica support were uniquely revealed using electron tomography. These anatase nanoparticle bearing films showed photocatalytic activity in methylene blue degradation. This new synthesis procedure of the anatase nanophase in mesoporous silica films using ALD is a convenient fabrication method of photocatalytic coatings amenable to application on very small as well as very large surfaces
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 7.367
Times cited: 22
DOI: 10.1039/c3nr00594a
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“Method to quantify the delocalization of electronic states in amorphous semiconductors and its application to assessing charge carrier mobility of p-type amorphous oxide semiconductors”. de de Meux AJ, Pourtois G, Genoe J, Heremans P, Physical review B 97, 045208 (2018). http://doi.org/10.1103/PHYSREVB.97.045208
Abstract: Amorphous semiconductors are usually characterized by a low charge carrier mobility, essentially related to their lack of long-range order. The development of such material with higher charge carrier mobility is hence challenging. Part of the issue comes from the difficulty encountered by first-principles simulations to evaluate concepts such as the electron effective mass for disordered systems since the absence of periodicity induced by the disorder precludes the use of common concepts derived from condensed matter physics. In this paper, we propose a methodology based on first-principles simulations that partially solves this problem, by quantifying the degree of delocalization of a wave function and of the connectivity between the atomic sites within this electronic state. We validate the robustness of the proposed formalism on crystalline and molecular systems and extend the insights gained to disordered/amorphous InGaZnO4 and Si. We also explore the properties of p-type oxide semiconductor candidates recently reported to have a low effective mass in their crystalline phases [G. Hautier et al., Nat. Commun. 4, 2292 (2013)]. Although in their amorphous phase none of the candidates present a valence band with delocalization properties matching those found in the conduction band of amorphous InGaZnO4, three of the seven analyzed materials show some potential. The most promising candidate, K2Sn2O3, is expected to possess in its amorphous phase a slightly higher hole mobility than the electron mobility in amorphous silicon.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.836
Times cited: 2
DOI: 10.1103/PHYSREVB.97.045208
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“Efficient amorphous platinum catalyst cluster growth on porous carbon : a combined molecular dynamics and experimental study”. Xie L, Brault P, Coutanceau C, Bauchire J-M, Caillard A, Baranton S, Berndt J, Neyts EC, Applied catalysis : B : environmental 162, 21 (2015). http://doi.org/10.1016/j.apcatb.2014.06.032
Abstract: Amorphous platinum clusters supported on porous carbon have been envisaged for high-performance fuel cell electrodes. For this application, it is crucial to control the morphology of the Pt layer and the Ptsubstrate interaction to maximize activity and stability. We thus investigate the morphology evolution during Pt cluster growth on a porous carbon substrate employing atomic scale molecular dynamics simulations. The simulations are based on the Pt-C interaction potential using parameters derived from density functional theory and are found to yield a Pt cluster morphology similar to that observed in low loaded fuel cell electrodes prepared by plasma sputtering. Moreover, the simulations show amorphous Pt cluster growth in agreement with X-ray diffraction and transmission electron microscopy experiments on high performance low Pt content (10 μgPt cm−2) loaded fuel cell electrodes and provide a fundamental insight in the cluster growth mechanism.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 9.446
Times cited: 20
DOI: 10.1016/j.apcatb.2014.06.032
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