“Preparation, structural and optical characterization of nanocrystalline ZnO doped with luminescent Ag-nanoclusters”. Kuznetsov AS, Lu Y-G, Turner S, Shestakov MV, Tikhomirov VK, Kirilenko D, Verbeeck J, Baranov AN, Moshchalkov VV, Optical materials express 2, 723 (2012). http://doi.org/10.1364/OME.2.000723
Abstract: Nanocrystalline ZnO doped with Ag-nanoclusters has been synthesized by a salt solid state reaction. Three overlapping broad emission bands due to the Ag nanoclusters have been detected at about 570, 750 and 900 nm. These emission bands are excited by an energy transfer from the exciton state of the ZnO host when pumped in the wavelength range from 250 to 400 nm. The 900 nm emission band shows characteristic orbital splitting into three components pointing out that the anisotropic crystalline wurtzite host of ZnO is responsible for this feature. Heat-treatment and temperature dependence studies confirm the origin of these emission bands. An energy level diagram for the emission process and a model for Ag nanoclusters sites are suggested. The emission of nanocrystalline ZnO doped with Ag nanoclusters may be applied for white light generation, displays driven by UV light, down-convertors for solar cells and luminescent lamps.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.591
DOI: 10.1364/OME.2.000723
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“Stability of Sb-Te layered structures : first-principles study”. Govaerts K, Sluiter MHF, Partoens B, Lamoen D, Physical review : B : condensed matter and materials physics 85, 144114 (2012). http://doi.org/10.1103/PhysRevB.85.144114
Abstract: Using an effective one-dimensional cluster expansion in combination with first-principles electronic structure calculations we have studied the energetics and electronic properties of Sb-Te layered systems. For a Te concentration between 0 and 60 at. % an almost continuous series of metastable structures is obtained consisting of consecutive Sb bilayers next to consecutive Sb2Te3 units, with the general formula (Sb-2)(n)(Sb2Te3)(m) (n, m = 1,2, ... ). Between 60 and 100 at.% no stable structures are found. We account explicitly for the weak van derWaals bonding between Sb bilayers and Sb2Te3 units by using a recently developed functional, which strongly improves the interlayer bonding distances. At T = 0 K, no evidence is found for the existence of two separate single-phase regions delta and gamma and a two-phase region delta + gamma. Metastable compounds with a Te concentration between 0 and 40 at. % are semimetallic, whereas compounds with a Te concentration between 50 and 60 at. % are semiconducting. Compounds with an odd number of Sb layers are metallic and have a much higher formation energy than those with an even number of consecutive Sb layers, thereby favoring the formation of Sb bilayers.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 14
DOI: 10.1103/PhysRevB.85.144114
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“Transition from single-file to two-dimensional diffusion of interacting particles in a quasi-one-dimensional channel”. Lucena D, Tkachenko DV, Nelissen K, Misko VR, Ferreira WP, Farias GA, Peeters FM, Physical review : E : statistical, nonlinear, and soft matter physics 85, 031147 (2012). http://doi.org/10.1103/PhysRevE.85.031147
Abstract: Diffusive properties of a monodisperse system of interacting particles confined to a quasi-one-dimensional channel are studied using molecular dynamics simulations. We calculate numerically the mean-squared displacement (MSD) and investigate the influence of the width of the channel (or the strength of the confinement potential) on diffusion in finite-size channels of different shapes (i.e., straight and circular). The transition from single-file diffusion to the two-dimensional diffusion regime is investigated. This transition [ regarding the calculation of the scaling exponent (alpha) of the MSD <Delta x(2)(t)> proportional to t(alpha)] as a function of the width of the channel is shown to change depending on the channel's confinement profile. In particular, the transition can be either smooth (i.e., for a parabolic confinement potential) or rather sharp (i.e., for a hard-wall potential), as distinct from infinite channels where this transition is abrupt. This result can be explained by qualitatively different distributions of the particle density for the different confinement potentials.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.366
Times cited: 38
DOI: 10.1103/PhysRevE.85.031147
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“Tuning the pore size of ink-bottle mesopores by atomic layer deposition”. Dendooven J, Goris B, Devloo-Casier K, Levrau E, Biermans E, Baklanov MR, Ludwig KF, van der Voort P, Bals S, Detavernier C, Chemistry of materials 24, 1992 (2012). http://doi.org/10.1021/cm203754a
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 52
DOI: 10.1021/cm203754a
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“Vortex states in axially symmetric superconductors in applied magnetic field”. Ludu A, Milošević, MV, Peeters FM, Sn –, 0378-4754 82, 1258 (2012). http://doi.org/10.1016/j.matcom.2012.02.001
Abstract: We solve analytically the linearized Ginzburg-Landau (GL) equation in the presence of an uniform magnetic field with cylindrical boundary conditions. The solution of the non-linear GL equation is provided as an expansion in the basis of linearized solutions. We present examples of the resulting vortex structure for a solid and perforated superconducting cylinder. (C) 2012 IMACS. Published by Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.218
Times cited: 1
DOI: 10.1016/j.matcom.2012.02.001
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“Aptasensing of chloramphenicol in the presence of its analogues : reaching the maximum residue limit”. Pilehvar S, Mehta J, Dardenne F, Robbens J, Blust R, De Wael K, Analytical chemistry 84, 6753 (2012). http://doi.org/10.1021/AC3012522
Abstract: A novel label-free folding induced aptamer-based electrochemical biosensor for the detection of chloramphenicol (CAP) in the presence of its analogues has been developed. CAP is a broad-spectrum antibiotic which has lost its favor due to its serious adverse toxic effects on human health. Aptamers are artificial nucleic acid ligands (ssDNA or RNA) able to specifically recognize a target such as CAP. In this article, the aptamers are fixed onto a gold electrode surface by a self-assembly approach. In the presence of CAP, the unfolded ssDNA on the electrode surface changes to a hairpin structure bringing the target molecules close to the surface and trigger electron transfer. Detection limits were determined to be 1.6×10-9 mol L-1. In addition, thiamphenicol (TAP) and florfenicol (FF), antibiotics with a similar structure to CAP, did not influence the performance of the aptasensor, suggesting a good selectivity of the CAP-aptasensor. Simplicity and lower detection limit (because of the home-selected aptamers) make that the electrochemical aptasensor is suitable for practical use in the detection of CAP in milk samples.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 6.32
Times cited: 68
DOI: 10.1021/AC3012522
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“Electrochemical sensing of phenicol antibiotics at gold”. Pilehvar S, Dardenne F, Blust R, De Wael K, International journal of electrochemical science 7, 5000 (2012)
Abstract: Phenicols are an effective and a broad spectrum class of antibiotics which has lost favour due to their side effects on human health. A rapid and sensitive electrochemical detection system is developed for the simultaneous detection of chloramphenicol (CAP), thiamphenicol (TAP) and florfenicol (FF). The electrochemical behaviour of CAP in the presence of its derivatives was investigated by cyclic voltammetry (CV) and square wave voltammetry (SWV). At a gold electrode, CAP gives rise to a sensitive cathodic peak at −0.68V (versus SCE) in a tris buffer solution (pH 7.6). This behavior gives us the opportunity to introduce a method for sensing CAP electrochemically in the presence of its derivatives. Calibration graphs were linear in the 2.5-7.4 μmol L-1 concentration range. Deviations from linearity were observed for higher concentrations and this was interpreted to be due to kinetic limitation caused by the saturation of CAP and its reduction products onto the gold electrode surface. A limit of detection of 1 μmol L-1 was found.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 1.469
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“Fabrication of perovskite capillary membranes for high temperature gas separation”. Van Noyen J, Middelkoop V, Buysse C, Kovalevsky A, Snijkers F, Buekenhoudt A, Mullens S, Luyten J, Kretzschmar J, Lenaerts S, Catalysis today 193, 172 (2012). http://doi.org/10.1016/J.CATTOD.2012.03.005
Abstract: Oxygen-permeable perovskites with mixed ionic-electronic conducting properties can play an important role in carbon capture and storage techniques. Their ability to separate oxygen from air is needed, more specifically, in oxy-fuel and pre-combustion technologies. In this work, the first detailed comparative analysis and new results are reported on four types of Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) capillary membranes: non-coated sulphur-containing; catalyst-coated sulphur-containing; non-coated sulphur-free and catalyst-coated sulphur-free. The fabrication of BSCF capillaries by a spinning technique based on phase inversion is further discussed and their oxygen separation performances are interpreted. The comparison of the performance of these different generations of BSCF capillaries of similar dimensions demonstrates a significant impact of the sulphur contamination on both the oxygen flux through the membrane and the activation energy of the overall oxygen transport mechanism. Careful attention is paid to the effect of activation layers on both sulphur-free and sulphur-containing types of capillaries. Additional long-term testing of the sulphur-free BSCF capillaries is presented, where partial decomposition of the membrane surface was observed due to kinetic demixing. (c) 2012 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 4.636
Times cited: 9
DOI: 10.1016/J.CATTOD.2012.03.005
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“Dielectric barrier discharges used for the conversion of greenhouse gases: modeling the plasma chemistry by fluid simulations”. De Bie C, Martens T, van Dijk J, Paulussen S, Verheyde B, Corthals S, Bogaerts A, Plasma sources science and technology 20, 024008 (2011). http://doi.org/10.1088/0963-0252/20/2/024008
Abstract: The conversion of methane to value-added chemicals and fuels is considered to be one of the challenges of the 21st century. In this paper we study, by means of fluid modeling, the conversion of methane to higher hydrocarbons or oxygenates by partial oxidation with CO2 or O2 in a dielectric barrier discharge. Sixty-nine different plasma species (electrons, ions, molecules, radicals) are included in the model, as well as a comprehensive set of chemical reactions. The calculation results presented in this paper include the conversion of the reactants and the yields of the reaction products as a function of residence time in the reactor, for different gas mixing ratios. Syngas (i.e. H2 + CO) and higher hydrocarbons (C2Hx) are typically found to be important reaction products.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.302
Times cited: 38
DOI: 10.1088/0963-0252/20/2/024008
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“Fluid modeling of the conversion of methane into higher hydrocarbons in an atmospheric pressure dielectric barrier discharge”. De Bie C, Verheyde B, Martens T, van Dijk J, Paulussen S, Bogaerts A, Plasma processes and polymers 8, 1033 (2011). http://doi.org/10.1002/ppap.201100027
Abstract: A one-dimensional fluid model for a dielectric barrier discharge in methane, used as a chemical reactor for gas conversion, is developed. The model describes the gas phase chemistry governing the conversion process of methane to higher hydrocarbons. The spatially averaged densities of the various plasma species as a function of time are discussed. Besides, the conversion of methane and the yields of the reaction products as a function of the residence time in the reactor are shown and compared with experimental data. Higher hydrocarbons (C2Hy and C3Hy) and hydrogen gas are typically found to be important reaction products. Furthermore, the main underlying reaction pathways are determined.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.846
Times cited: 70
DOI: 10.1002/ppap.201100027
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“Optimized fabrication of high-quality La0.67Sr0.33MnO3 thin films considering all essential characteristics”. Boschker H, Huijben M, Vailinois A, Verbeeck J, Van Aert S, Luysberg M, Bals S, Van Tendeloo G, Houwman EP, Koster G, Blank DHA, Rijnders G, Journal of physics: D: applied physics 44, 205001 (2011). http://doi.org/10.1088/0022-3727/44/20/205001
Abstract: In this paper, an overview of the fabrication and properties of high-quality La0.67Sr0.33MnO3 (LSMO) thin films is given. A high-quality LSMO film combines a smooth surface morphology with a large magnetization and a small residual resistivity, while avoiding precipitates and surface segregation. In the literature, typically only a few of these issues are adressed. We therefore present a thorough characterization of our films, which were grown by pulsed laser deposition. The films were characterized with reflection high energy electron diffraction, atomic force microscopy, x-ray diffraction, magnetization and transport measurements, x-ray photoelectron spectroscopy and scanning transmission electron microscopy. The films have a saturation magnetization of 4.0 µB/Mn, a Curie temperature of 350 K and a residual resistivity of 60 µΩ cm. These results indicate that high-quality films, combining both large magnetization and small residual resistivity, were realized. A comparison between different samples presented in the literature shows that focussing on a single property is insufficient for the optimization of the deposition process. For high-quality films, all properties have to be adressed. For LSMO devices, the thin-film quality is crucial for the device performance. Therefore, this research is important for the application of LSMO in devices.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.588
Times cited: 99
DOI: 10.1088/0022-3727/44/20/205001
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“Unprecedented shape selectivity in hydrogenation of triacylglycerol molecules with Pt/ZSM-5 zeolite”. Philippaerts A, Paulussen S, Breesch A, Turner S, Lebedev OI, Van Tendeloo G, Sels B, Jacobs P, Angewandte Chemie: international edition in English 50, 3947 (2011). http://doi.org/10.1002/anie.201007513
Abstract: Well tuned: ZSM-5 with platinum nanoparticles preferably hydrogenates trans fatty acids over cis isomers in model triacylglycerols for geometric reasons. The central fatty acid chain reacts faster, pointing to pore mouth adsorption in a tuning fork conformation (see picture). This conformation induces stepwise hydrogenation, resulting in fast removal of the unstable central triene, while formation of saturated chains is limited.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 11.994
Times cited: 31
DOI: 10.1002/anie.201007513
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“Development, performance and stability of sulfur-free, macrovoid-free BSCF capillaries for high temperature oxygen separation from air”. Buysse C, Kovalevsky A, Snijkers F, Buekenhoudt A, Mullens S, Luyten J, Kretzschmar J, Lenaerts S, Journal of membrane science 372, 239 (2011). http://doi.org/10.1016/J.MEMSCI.2011.02.011
Abstract: Capture and storage of CO2 (CCS) from fossil-fuel power plants is vital in order to counteract a pending anthropogenic global warming. High temperature oxygen transport perovskite membranes can fulfill an important role in the separation of oxygen from air needed in the oxy-fuel technologies for CCS. In this study we present the development, performance and stability of gastight, macrovoid-free and sulfur-free Ba0.5Sr0.5Co0.8Fe0.2O3 − δ (BSCF) mixed conductor capillary membranes prepared by phase-inversion spinning and sintering. A sulfur-free phase-inversion polymer was chosen in order to obtain a phase-pure BSCF crystal phase. Special attention was given to the polymer solution and ceramic spinning suspension in order to avoid macrovoids and achieve gastight membranes. The sulfur-free BSCF capillaries showed an average 4-point bending strength of 64 ± 8 MPa and a maximum oxygen flux of not, vert, similar5.3 Nml/(cm2 min) at 950 °C for an argon sweep flow rate of 125 Nml/min. The comparison of the performance of sulfur-free and sulfur-containing BSCF capillaries with similar dimensions revealed a profound impact of the sulfur contamination on both the oxygen flux and the activation energy of the overall oxygen transport mechanism. Both long-term oxygen permeation at different temperatures and post-operation analysis of a sulfur-free BSCF capillary were performed and discussed.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 6.035
Times cited: 32
DOI: 10.1016/J.MEMSCI.2011.02.011
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“Oxygen exchange-limited transport and surface activation of Ba0.5Sr0.5Co0.8Fe0.2O3-\delta capillary membranes”. Kovalevsky A, Buysse C, Snijkers F, Buekenhoudt A, Luyten J, Kretzschmar J, Lenaerts S, Journal of membrane science 368, 223 (2011). http://doi.org/10.1016/J.MEMSCI.2010.11.034
Abstract: Analysis of oxygen permeation fluxes through Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) capillary membranes, fabricated via a phase-inversion spinning technique using polysulfone as binder, showed a significant limiting role of the surface-oxygen exchange kinetics. Within the studied temperature and oxygen partial pressure ranges, the activation of core and shell sides of the BSCF capillary with praseodymium oxide (PrOx) resulted in an increase in permeation rate of about 300%. At 11231223 K the activated BSCF membranes demonstrate almost 3-times lower activation energies for the overall oxygen transport (not, vert, similar35 kJ/mol) than the non-activated capillaries, indicating that the mechanism of oxygen transport through the activated capillaries becomes significantly controlled by bulk diffusion limitations, allowing further improvement of the overall performance by decreasing the wall thickness. XRD, EDS and EPMA studies revealed the formation of (Pr,Ba,Sr)(Co,Fe)O3−δ perovskite-type oxides on the surface of the PrOx-modified membranes, which may be responsible for the drastic increase in oxygen exchange rate. At T > 1123 K both non-activated and activated Ba0.5Sr0.5Co0.8Fe0.2O3−δ membranes demonstrate stable performance with time, while at 1073 K only a small initial decrease in permeation was observed.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 6.035
Times cited: 21
DOI: 10.1016/J.MEMSCI.2010.11.034
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“Mapping of toxic vapours on board of tankers”. Jacobs W, Floren E, Luyckx D, Bueken P, van Beeck J, Van Grieken R, (2011)
Keywords: P3 Proceeding; Economics; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
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“Analytic treatment of vortex states in cylindrical superconductors in applied axial magnetic field”. Ludu A, Van Deun J, Milošević, MV, Cuyt A, Peeters FM, Journal of mathematical physics 51, 082903 (2010). http://doi.org/10.1063/1.3470767
Abstract: We solve the linear GinzburgLandau (GL) equation in the presence of a uniform magnetic field with cylindrical symmetry and we find analytic expressions for the eigenfunctions in terms of the confluent hypergeometric functions. The discrete spectrum results from an implicit equation associated to the boundary conditions and it is resolved in analytic form using the continued fractions formalism. We study the dependence of the spectrum and the eigenfunctions on the sample size and the surface conditions for solid and hollow cylindrical superconductors. Finally, the solutions of the nonlinear GL formalism are constructed as expansions in the linear GL eigenfunction basis and selected by minimization of the free energy. We present examples of vortex states and their energies for different samples in enhancing/suppressing superconductivity surroundings.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.077
Times cited: 10
DOI: 10.1063/1.3470767
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“Conversion of carbon dioxide to value-added chemicals in atmospheric pressure dielectric barrier discharges”. Paulussen S, Verheyde B, Tu X, De Bie C, Martens T, Petrovic D, Bogaerts A, Sels B, Plasma sources science and technology 19, 034015 (2010). http://doi.org/10.1088/0963-0252/19/3/034015
Abstract: The aim of this work consists of the evaluation of atmospheric pressure dielectric barrier discharges for the conversion of greenhouse gases into useful compounds. Therefore, pure CO2 feed flows are administered to the discharge zone at varying discharge frequency, power input, gas temperature and feed flow rates, aiming at the formation of CO and O2. The discharge obtained in CO2 is characterized as a filamentary mode with a microdischarge zone in each half cycle of the applied voltage. It is shown that the most important parameter affecting the CO2-conversion levels is the gas flow rate. At low flow rates, both the conversion and the CO-yield are significantly higher. In addition, also an increase in the gas temperature and the power input give rise to higher conversion levels, although the effect on the CO-yield is limited. The optimum discharge frequency depends on the power input level and it cannot be unambiguously stated that higher frequencies give rise to increased conversion levels. A maximum CO2 conversion of 30% is achieved at a flow rate of 0.05 L min−1, a power density of 14.75 W cm−3 and a frequency of 60 kHz. The most energy efficient conversions are achieved at a flow rate of 0.2 L min−1, a power density of 11 W cm−3 and a discharge frequency of 30 kHz.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.302
Times cited: 116
DOI: 10.1088/0963-0252/19/3/034015
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“Electronic reconstruction at n-type SrTiO3/LaAlO3 interfaces”. Verbeeck J, Bals S, Lamoen D, Luysberg M, Huijben M, Rijnders G, Brinkman A, Hilgenkamp H, Blank DHA, Van Tendeloo G, Physical review : B : condensed matter and materials physics 81, 085113 (2010). http://doi.org/10.1103/PhysRevB.81.085113
Abstract: Electron-energy-loss spectroscopy (EELS) is used to investigate single layers of LaAlO3 grown on SrTiO3 having an n-type interface as well as multilayers of LaAlO3 and SrTiO3 in which both n- and p-type interfaces occur. Only minor changes in Ti valence at the n-type interface are observed. This finding seems to contradict earlier experiments for other SrTiO3/LaAlO3 systems where large deviations in Ti valency were assumed to be responsible for the conductivity of these interfaces. Ab initio calculations have been carried out in order to interpret our EELS results. Using the concept of Bader charges, it is demonstrated that the so-called polar discontinuity is mainly resolved by lattice distortions and to a far lesser extent by changes in valency for both single layer and multilayer geometries.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 25
DOI: 10.1103/PhysRevB.81.085113
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“Experimental observation of single-file water filling of thin single-wall carbon nanotubes down to chiral index (5,3)”. Cambré, S, Schoeters B, Luyckx S, Goovaerts E, Wenseleers W, Physical review letters 104, 207401 (2010). http://doi.org/10.1103/PhysRevLett.104.207401
Abstract: Single-file transport of water into carbon nanotubes is experimentally demonstrated for the first time through the splitting of the radial breathing mode (RBM) vibration in Raman spectra of bile salt solubilized tubes when both empty (closed) and water-filled (open-ended) tubes are present. D2O filling is observed for a wide range of diameters, d, down to very thin tubes [e.g., (5,3) tube, d=0.548 nm] for which only a single water molecule fits in the cross section of the internal nanotube channel. The shift in RBM frequency upon filling is found to display a very complex dependence on nanotube diameter and chirality, in support of a different yet well-defined ordering and orientation of water molecules at room temperature. Large shifts of the electronic transitions are also observed.
Keywords: A1 Journal article; Particle Physics Group; Nanostructured and organic optical and electronic materials (NANOrOPT); Condensed Matter Theory (CMT)
Impact Factor: 8.462
Times cited: 140
DOI: 10.1103/PhysRevLett.104.207401
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“Formation of stripelike flux patterns obtained by freezing kinematic vortices in a superconducting Pb film”. Silhanek AV, Milošević, MV, Kramer RBG, Berdiyorov GR, Vondel van de J, Luccas RF, Puig T, Peeters FM, Moshchalkov VV, Physical review letters 104 (2010). http://doi.org/10.1103/PhysRevLett.104.017001
Abstract: We demonstrate experimentally and theoretically that the dissipative state of superconducting samples with a periodic array of holes at high current densities consists of flux rivers resulting from a short-range attractive interaction between vortices. This dynamically induced vortex-vortex attraction results from the migration of quasiparticles out of the vortex core (kinematic vortices). We have directly visualized the formation of vortex chains by scanning Hall probe microscopy after freezing the dynamic state by a field cooling procedure at a constant bias current. Similar experiments carried out in a sample without holes show no hint of flux river formation. We shed light on this nonequilibrium phenomena modeled by time-dependent Ginzburg-Landau simulations.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 8.462
Times cited: 60
DOI: 10.1103/PhysRevLett.104.017001
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“Freezing vortex rivers”. Silhanek AV, Kramer RGB, van de Vondel J, Moshchalkov VV, Milošević, MV, Berdiyorov GR, Peeters FM, Luccas RF, Puig T, Physica: C : superconductivity 470, 726 (2010). http://doi.org/10.1016/j.physc.2010.02.072
Abstract: We demonstrate experimentally and theoretically that the dissipative state at high current densities of superconducting samples with a periodic array of holes consist of flux rivers resulting from a short range attractive interaction between vortices. This dynamically induced vortexvortex attraction results from the migration of quasiparticles out of the vortex core. We have directly visualized the formation of vortex chains by scanning Hall microscopy after freezing the dynamic state by a field cooling procedure at constant bias current. Similar experiments carried out in a sample without holes show no hint of flux river formation.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.404
Times cited: 4
DOI: 10.1016/j.physc.2010.02.072
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“Morphological transformations and fusion of PbSe nanocrystals studied using atomistic simulations”. Schapotschnikow P, van Huis MA, Zandbergen HW, Vanmaekelbergh D, Vlugt TJH, Nano letters 10, 3966 (2010). http://doi.org/10.1021/nl101793b
Abstract: Molecular dynamics simulations are performed on capped and uncapped PbSe nanocrystals, employing newly developed classical interaction potentials. Here, we show that two uncapped nanocrystals fuse efficiently via direct surface attachment, even if they are initially misaligned. In sharp contrast to the general belief, interparticle dipole interactions do not play a significant role in this oriented attachment process. Furthermore, it is shown that presumably polar, capped PbSe{111} facets are never fully Pb- or Se-terminated.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 12.712
Times cited: 59
DOI: 10.1021/nl101793b
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“Origin of predominance of cementite among iron carbides in steel at elevated temperature”. Fang CM, Sluiter MHF, van Huis M, Ande CK, Zandbergen HW, Physical review letters 105, 4 (2010). http://doi.org/10.1103/PhysRevLett.105.055503
Abstract: A long-standing challenge in physics is to understand why cementite is the predominant carbide in steel. Here we show that the prevalent formation of cementite can be explained only by considering its stability at elevated temperature. A systematic highly accurate quantum mechanical study was conducted on the stability of binary iron carbides. The calculations show that all the iron carbides are unstable relative to the elemental solids, -Fe and graphite. Apart from a cubic Fe23C6 phase, the energetically most favorable carbides exhibit hexagonal close-packed Fe sublattices. Finite-temperature analysis showed that contributions from lattice vibration and anomalous Curie-Weis magnetic ordering, rather than from the conventional lattice mismatch with the matrix, are the origin of the predominance of cementite during steel fabrication processes.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 8.462
Times cited: 65
DOI: 10.1103/PhysRevLett.105.055503
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“Selectivity in sorption and hydrogenation of methyl oleate and elaidate on MFI zeolites”. Philippaerts A, Paulussen S, Turner S, Lebedev OI, Van Tendeloo G, Poelman H, Bulut M, de Clippel F, Smeets P, Sels B, Jacobs P, Journal of catalysis 270, 172 (2010). http://doi.org/10.1016/j.jcat.2009.12.022
Abstract: Different zeolites were tested for selective removal of methyl elaidate (trans isomer) from an equimolar mixture with methyl oleate (cis isomer). Sorption experiments of the geometric isomers show that only ZSM-5 samples with reduced Al content in the framework are able to discriminate among the bent cis and the linear trans fatty acid methyl esters. Hydrogenation experiments of equimolar methyl oleate and elaidate mixtures at low temperature (65 °C) and high hydrogen pressure (6.0 MPa), using Pt catalysts, confirm this result. Only with a Pt/NaZSM-5 catalyst outspoken selectivity for the hydrogenation of the trans isomer is obtained. In order to prepare a selective Pt/ZSM-5 catalyst, the influence of Pt addition (impregnation, ion-exchange and competitive ion-exchange) and Pt activation (different calcination and reduction temperatures) on the Pt-distribution and Pt particle size was investigated using SEM, bright-field and HR TEM, EDX, electron tomography, CO-chemisorption, XPS, XRD, and UVvis measurements. The best result in terms of hydrogenation activity and selectivity is obtained with a Pt/ZSM-5 catalyst, which is prepared via competitive ion-exchange, followed by slow calcination up to 350 °C under high O2 flow and a reduction up to 500 °C under H2. This preparation method leads to a Pt/ZSM-5 catalyst with the best Pt distribution and the smallest Pt clusters occluded in the zeolite structure. Finally, the influence of zeolite crystal size, morphology, and elemental composition of ZSM-5 on hydrogenation activity and selectivity was investigated in detail.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 6.844
Times cited: 24
DOI: 10.1016/j.jcat.2009.12.022
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“Fabrication and oxygen permeability of gastight, macrovoid-free Ba0.5Sr0.5Co0.8Fe0.2O3-\delta capillaries for high temperature gas separation”. Buysse C, Kovalevsky A, Snijkers F, Buekenhoudt A, Mullens S, Luyten J, Kretzschmar J, Lenaerts S, Journal of membrane science 359, 86 (2010). http://doi.org/10.1016/J.MEMSCI.2009.10.030
Abstract: Oxygen-permeable perovskites with mixed ionic-electronic conducting properties can play an important role in the separation of oxygen from air which is needed in the oxy-fuel and pre-combustion technologies for the removal and capture of CO2. In this work, gastight, macrovoid-free Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) capillaries were successfully shaped by a phase-inversion spinning technique, followed by calcination and sintering. It was found that both the rheology of the ceramic suspension and the composition of bore liquid and coagulation bath are key factors for making macrovoid-free green capillaries. Gastight BSCF capillaries were obtained by sintering for 5 h at 1100 °C. The sintered BSCF capillaries contained a significant amount of BaSO4 due to a reaction with the polysulfone binder during calcination. The oxygen permeation flux through the BSCF capillaries was measured and compared to literature data on BSCF disk and hollow fiber membranes measured in similar conditions.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 6.035
Times cited: 38
DOI: 10.1016/J.MEMSCI.2009.10.030
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“Pyrolysis kinetics of bamboo material”. Potters G, Schoeters G, Tytgat T, Horvath G, Ludecke C, Cool P, Lenaerts S, Appels L, Dewil R, (2010)
Keywords: P3 Proceeding; Engineering sciences. Technology; Laboratory of adsorption and catalysis (LADCA); Sustainable Energy, Air and Water Technology (DuEL)
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“Control and readout of current-induced magnetic flux quantization in a superconducting transformer”. Kerner C, Hackens B, Golubović, DS, Poli S, Faniel S, Magnus W, Schoenmaker W, Bayot V, Maes H, Superconductor science and technology 22, 025001 (2009). http://doi.org/10.1088/0953-2048/22/2/025001
Abstract: We demonstrate a simple and robust method for inducing and detecting changes of magnetic flux quantization in the absence of an externally applied magnetic field. In our device, an isolated ring is interconnected with two access loops via permalloy cores, forming a superconducting transformer. By applying and tuning a direct current at the first access loop, the number of flux quanta trapped in the isolated ring is modified without the aid of an external field. The flux state of the isolated ring is simply detected by recording the evolution of the critical current of the second access loop.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.878
Times cited: 2
DOI: 10.1088/0953-2048/22/2/025001
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“Dependence of resistivity on electron density and temperature in graphene”. Xu W, Peeters FM, Lu TC, Physical review : B : solid state 79, 073403 (2009). http://doi.org/10.1103/PhysRevB.79.073403
Abstract: On the basis of the momentum-balance equation derived from the Boltzmann equation in which electron interactions with impurities and acoustic and optic phonons are included, we examine the dependence of the resistivity in graphene on temperature and electron density. Simple analytical expressions for the different contributions to the resistivity are obtained. Our results reproduce recent experimental findings and we are able to understand the different temperature dependence of the resistivity for low and high density samples.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 31
DOI: 10.1103/PhysRevB.79.073403
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“Enamels in stained glass windows: preparation, chemical composition, microstructure and causes of deterioration”. Schalm O, van der Linden V, Frederickx P, Luyten S, van der Snickt G, Caen J, Schryvers D, Janssens K, Cornelis E, van Dyck D, Schreiner M, Spectrochimica acta: part B : atomic spectroscopy 64, 812 (2009). http://doi.org/10.1016/j.sab.2009.06.005
Abstract: Stained glass windows incorporating dark blue and purple enamel paint layers are in some cases subject to severe degradation while others from the same period survived the ravages of time. A series of dark blue, greenblue and purple enamel glass paints from the same region (Northwestern Europe) and from the same period (16early 20th centuries) has been studied by means of a combination of microscopic X-ray fluorescence analysis, electron probe micro analysis and transmission electron microscopy with the aim of better understanding the causes of the degradation. The chemical composition of the enamels diverges from the average chemical composition of window glass. Some of the compositions appear to be unstable, for example those with a high concentration of K2O and a low content of CaO and PbO. In other cases, the deterioration of the paint layers was caused by the less than optimal vitrification of the enamel during the firing process. Recipes and chemical compositions indicate that glassmakers of the 1617th century had full control over the color of the enamel glass paints they made. They mainly used three types of coloring agents, based on Co (dark blue), Mn (purple) and Cu (light-blue or greenblue) as coloring elements. Bluepurple enamel paints were obtained by mixing two different coloring agents. The coloring agent for redpurple enamel, introduced during the 19th century, was colloidal gold embedded in grains of lead glass.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Vision lab
Impact Factor: 3.241
Times cited: 28
DOI: 10.1016/j.sab.2009.06.005
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“Hepatocellular transport and gastrointestinal absorption of lanthanum in chronic renal failure”. Bervoets ARJ, Behets GJ, Schryvers D, Roels F, Yang Z, Verberckmoes SC, Damment SJP, Dauwe S, Mubiana VK, Blust R, de Broe ME, d' Haese PC, Kidney international 75, 389 (2009). http://doi.org/10.1038/ki.2008.571
Abstract: Lanthanum carbonate is a new phosphate binder that is poorly absorbed from the gastrointestinal tract and eliminated largely by the liver. After oral treatment, we and others had noticed 23 fold higher lanthanum levels in the livers of rats with chronic renal failure compared to rats with normal renal function. Here we studied the kinetics and tissue distribution, absorption, and subcellular localization of lanthanum in the liver using transmission electron microscopy, electron energy loss spectrometry, and X-ray fluoresence. We found that in the liver lanthanum was located in lysosomes and in the biliary canal but not in any other cellular organelles. This suggests that lanthanum is transported and eliminated by the liver via a transcellular, endosomal-lysosomal-biliary canicular transport route. Feeding rats with chronic renal failure orally with lanthanum resulted in a doubling of the liver levels compared to rats with normal renal function, but the serum levels were similar in both animal groups. These levels plateaued after 6 weeks at a concentration below 3 g/g in both groups. When lanthanum was administered intravenously, thereby bypassing the gastrointestinal tract-portal vein pathway, no difference in liver levels was found between rats with and without renal failure. This suggests that there is an increased gastrointestinal permeability or absorption of oral lanthanum in uremia. Lanthanum levels in the brain and heart fluctuated near its detection limit with long-term treatment (20 weeks) having no effect on organ weight, liver enzyme activities, or liver histology. We suggest that the kinetics of lanthanum in the liver are consistent with a transcellular transport pathway, with higher levels in the liver of uremic rats due to higher intestinal absorption.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Pathophysiology
Impact Factor: 8.395
Times cited: 29
DOI: 10.1038/ki.2008.571
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