“Cation ordering within the perovskite block of a six-layer Ruddlesden-Popper oxide from layer-by-layer growth artificial interfaces in complex unit cells”. Yan L, Niu HJ, Duong GV, Suchomel MR, Bacsa J, Chalker PR, Hadermann J, Van Tendeloo G, Rosseinsky MJ, Chemical science 2, 261 (2011). http://doi.org/10.1039/c0sc00482k
Abstract: The (AO)(ABO3)n Ruddlesden-Popper structure is an archetypal complex oxide consisting of two distinct structural units, an (AO) rock salt layer separating an n-octahedra thick perovskite block. Conventional high-temperature oxide synthesis methods cannot access members with n > 3, but low-temperature layer-by-layer thin film methods allow the preparation of materials with thicker perovskite blocks, exploiting high surface mobility and lattice matching with the substrate. This paper describes the growth of an n = 6 member CaO[(CSMO)2(LCMO)2 (CSMO)2] in which the six unit cell perovskite block is sub-divided into two central La0.67Ca0.33MnO3 (LCMO) and two terminal Ca0.85Sm0.15MnO3 (CSMO) layers to allow stabilization of the rock salt layer and variation of the transition metal charge.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 8.668
Times cited: 16
DOI: 10.1039/c0sc00482k
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“Cation-controlled permeation of charged polymers through nanocapillaries”. Faraji F, Neek-Amal M, Neyts EC, Peeters FM, Physical review E 107, 034501 (2023). http://doi.org/10.1103/PHYSREVE.107.034501
Abstract: Molecular dynamics simulations are used to study the effects of different cations on the permeation of charged polymers through flat capillaries with heights below 2 nm. Interestingly, we found that, despite being monovalent, Li+ , Na+ , and K+ cations have different effects on polymer permeation, which consequently affects their transmission speed throughout those capillaries. We attribute this phenomenon to the interplay of the cations' hydration free energies and the hydrodynamic drag in front of the polymer when it enters the capillary. Different alkali cations exhibit different surface versus bulk preferences in small clusters of water under the influence of an external electric field. This paper presents a tool to control the speed of charged polymers in confined spaces using cations.
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.4
Times cited: 1
DOI: 10.1103/PHYSREVE.107.034501
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“Cationic clathrate of type-III Ge172-xPxTey (y\approx21,5, x\approx2y) : synthesis, crystal structure and thermoelectric properties”. Kirsanova MA, Mori T, Maruyama S, Abakumov AM, Van Tendeloo G, Olenev A, Shevelkov AV, Inorganic chemistry 52, 8272 (2013). http://doi.org/10.1021/ic401203r
Abstract: A first germanium-based cationic clathrate of type-III, Ge129.3P42.7Te21.53, was synthesized and structurally characterized (space group P42/mnm, a = 19.948(3) Å, c = 10.440(2) Å, Z = 1). In its crystal structure, germanium and phosphorus atoms form three types of polyhedral cages centered with Te atoms. The polyhedra share pentagonal and hexagonal faces to form a 3D framework. Despite the complexity of the crystal structure, the Ge129.3P42.7Te21.53 composition corresponds to the Zintl counting scheme with a good accuracy. Ge129.3P42.7Te21.53 demonstrates semiconducting/insulating behavior of electric resistivity, high positive Seebeck coefficient (500 μV K1 at 300 K), and low thermal conductivity (<0.92 W m1 K1) within the measured temperature range.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4.857
Times cited: 3
DOI: 10.1021/ic401203r
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“Causal loop diagrams to systematically analyze market power in the Belgian sugar value chain”. Biely K, Mathijs E, Van Passel S, AIMS Agriculture and Food 4, 711 (2019). http://doi.org/10.3934/AGRFOOD.2019.3.711
Abstract: It has been acknowledged that power is a fundamental aspect that needs to be considered when performing a value chain analysis. The structure of the value chain is indicative of the power distribution along the chain. By employing systems thinking the structure of the value chain can be further investigated and inferences on market power issues can be made. This novel approach connects value chain research with insights from Industrial Organization (IO) literature. Depending on the case, market power may not be measurable by traditional economic tools. Systems thinking offers an alternative tool, allowing the employment of qualitative and quantitative data, overcoming drawbacks of IO methods and providing more depth to value chain analysis. In this paper the valuable contribution of systems thinking to market power analysis is exemplified by the Belgian sugar beet case. The analysis showed that transportability and perishability of sugar beet are key causes of market failure in the Belgian sugar value chain. Systems thinking can support understanding potential future behavior of the market based on the thorough understanding of the current market structure. We illustrate how to integrate factors determining the market structure into causal loop diagrams. This novel approach allows a comprehensive evaluation and thus opens up market power analysis to interdisciplinary research.
Keywords: A1 Journal article; Engineering Management (ENM)
DOI: 10.3934/AGRFOOD.2019.3.711
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“Causes and consequences of ordering and dynamic phases of confined vortex rows in superconducting nanostripes”. McNaughton B, Pinto N, Perali A, Milošević, MV, Nanomaterials 12, 4043 (2022). http://doi.org/10.3390/NANO12224043
Abstract: Understanding the behaviour of vortices under nanoscale confinement in superconducting circuits is important for the development of superconducting electronics and quantum technologies. Using numerical simulations based on the Ginzburg-Landau theory for non-homogeneous superconductivity in the presence of magnetic fields, we detail how lateral confinement organises vortices in a long superconducting nanostripe, presenting a phase diagram of vortex configurations as a function of the stripe width and magnetic field. We discuss why the average vortex density is reduced and reveal that confinement influences vortex dynamics in the dissipative regime under sourced electrical current, mapping out transitions between asynchronous and synchronous vortex rows crossing the nanostripe as the current is varied. Synchronous crossings are of particular interest, since they cause single-mode modulations in the voltage drop along the stripe in a high (typically GHz to THz) frequency range.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 5.3
Times cited: 2
DOI: 10.3390/NANO12224043
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“Cavity nucleation and growth in Cu-Zn-Al irradiated with Cu+ ions at different temperatures”. Zelaya E, Schryvers D, Tolley A, Fitchner PFP, Intermetallics 18, 493 (2010). http://doi.org/10.1016/j.intermet.2009.09.010
Abstract: The effects of high dose ion irradiation in β CuZnAl were investigated between room temperature and 150 °C. Single crystal samples with surface normal close to [001]β were irradiated with 300 keV Cu+ ions. Microstructural changes were characterized using transmission electron microscopy. Irradiation induced cavities located on the surface exposed to the irradiation were observed. The morphology, size and density distribution of these cavities were analyzed as a function of different irradiation conditions. The shape and location of the cavities with respect to the irradiation surface were not affected by irradiation temperature or irradiation dose. Instead, the cavity size distribution showed a bi-modal shape for a dose of 15 dpa, regardless of irradiation temperature. For a dose of 30 dpa the bi-modal distribution was only observed after room temperature irradiation. The diffusion effects of vacancies produced by irradiation are analyzed in shape memory CuZnAl alloys, which main characteristic is the diffusionless martensitic transformation. Particularly, the cavity size distributions were analyzed in terms of nucleation, growth and coalescence.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.14
Times cited: 1
DOI: 10.1016/j.intermet.2009.09.010
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“Ca6.3Mn3Ga4.4Al1.3O18: a novel complex oxide with 3D tetrahedral framework”. Abakumov AM, Hadermann J, Kalyuzhnaya AS, Rozova MG, Mikheev MG, Van Tendeloo G, Antipov EV, Journal of solid state chemistry 178, 3137 (2005). http://doi.org/10.1016/j.jssc.2005.07.028
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.299
Times cited: 5
DOI: 10.1016/j.jssc.2005.07.028
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“CdSe quantum dot formation induced by amorphous Se”. Aichele T, Robin I-C, Bougerol C, André, R, Tatarenko S, Van Tendeloo G, Surface science : a journal devoted to the physics and chemistry of interfaces
T2 –, International Conference on NANO-Structures Self Assembling, JUL 02-06, 2006, Aix en Provence, FRANCE 601, 2664 (2007). http://doi.org/10.1016/j.susc.2006.12.001
Abstract: The mechanism allowing the transition from a two-dimensional strained layer of CdSe on ZnSe to self-assembled islands induced by the use of amorphous selenium is still not fully understood. For a better understanding, atomic force microscopy and transmission electron microscopy studies were performed on CdSe films with a thickness close to that for quantum dot formation. Below this thickness, the sample surface results in undulations along the [110] crystal direction, while few quantum dots are situated in the wave valleys. Plan view transmission electron microscopy studies reveal a strong anisotropy of the islands and show that the Se desorption conditions are crucial. (C) 2006 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.062
DOI: 10.1016/j.susc.2006.12.001
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“CdSe quantum dot formation: alternative paths to relaxation of a strained CdSe layer and influence of the capping conditions”. Robin I-C, Aichele T, Bougerol C, André, R, Tatarenko S, Bellet-Amalric E, van Daele B, Van Tendeloo G, Nanotechnology 18, 265701 (2007). http://doi.org/10.1088/0957-4484/18/26/265701
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.44
Times cited: 8
DOI: 10.1088/0957-4484/18/26/265701
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“Centralised, decentralised or hybrid sanitation systems? Economic evaluation under urban development uncertainty and phased expansion”. Roefs I, Meulman B, Vreeburg JHG, Spiller M, Water research 109, 274 (2017). http://doi.org/10.1016/J.WATRES.2016.11.051
Abstract: Sanitation systems are built to be robust, that is, they are dimensioned to cope with population growth and other variability that occurs throughout their lifetime. It was recently shown that building sanitation systems in phases is more cost effective than one robust design. This phasing can take place by building small autonomous decentralised units that operate closer to the actual demand. Research has shown that variability and uncertainty in urban development does affect the cost effectiveness of this approach. Previous studies do not, however, consider the entire sanitation system from collection to treatment. The aim of this study is to assess the economic performance of three sanitation systems with different scales and systems characteristics under a variety of urban development pathways. Three systems are studied: (I) a centralised conventional activated sludge treatment, (II) a community on site source separation grey water and black water treatment and (III) a hybrid with grey water treatment at neighbourhood scale and black water treatment off site. A modelling approach is taken that combines a simulation of greenfield urban growth, a model of the wastewater collection and treatment infrastructure design properties and a model that translates design parameters into discounted asset lifetime costs. Monte Carlo simulations are used to evaluate the economic performance under uncertain development trends. Results show that the conventional system outperforms both of the other systems when total discounted lifetime costs are assessed, because it benefits from economies of scale. However, when population growth is lower than expected, the source-separated system is more cost effective, because of reduced idle capacity. The hybrid system is not competitive under any circumstance due to the costly double piping and treatment. (C) 2016 Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1016/J.WATRES.2016.11.051
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“Cephalosporin antibiotics : electrochemical fingerprints and core structure reactions investigated by LC-MSMS”. Sleegers N, van Nuijs ALN, van den Berg M, De Wael K, Analytical chemistry 91, 2035 (2019). http://doi.org/10.1021/ACS.ANALCHEM.8B04487
Abstract: Electrochemistry and exploiting electrochemical fingerprints is a potent approach to address newly emerging surveillance needs, for instance for antibiotics. However, a comprehensive insight in the electrochemical oxidation behaviour and mechanism is re-quired for this sensing strategy. To address the lack in knowledge of the voltammetric behaviour of the cephalosporins antibiotics, a selection of cephalosporin antibiotics and two main intermediates were subjected to an electrochemical study of their redox behaviour by means of pulsed voltammetric techniques and small-scale electrolysis combined with HPLC-MS/MS analyses. Sur-prisingly, the detected oxidation products did not fit the earlier suggested oxidation of the sulfur group to the corresponding sul-foxide. The influence of different side chains, both at the three and the seven position of the β-lactam core structure on the elec-trochemical fingerprint were investigated. Additional oxidation signals at lower potentials were elucidated and linked to different side chains. These signals were further exploited to allow simultaneous detection of different cephalosporins in one voltammetric sweep. These fundamental insights can become the building blocks for an new on-site screening method.
Keywords: A1 Journal article; Pharmacology. Therapy; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Toxicological Centre
Impact Factor: 6.32
Times cited: 6
DOI: 10.1021/ACS.ANALCHEM.8B04487
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Sleegers N (2021) Cephalosporin antibiotics : electrochemical fingerprints and redox pathways investigated by mass spectral analysis. 208 p
Keywords: Doctoral thesis; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab)
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“Ceramide cross-linking leads to pore formation: Potential mechanism behind CAP enhancement of transdermal drug delivery”. Van der Paal J, Fridman G, Bogaerts A, Plasma processes and polymers 16, 1900122 (2019). http://doi.org/10.1002/PPAP.201900122
Abstract: In recent years, cold atmospheric plasma (CAP) has been proposed as a novel method to enhance transdermal drug delivery, while avoiding tissue damage. However, the underlying mechanism for the increasing skin permeability upon CAP treatment is still undefined. We propose a mechanism in which CAP-generated reactive species induce cross-linking of skin lipids, leading to the generation of nanopores, thereby facilitating the permeation of drug molecules. Molecular dynamics simulations support this proposed mechanism. Furthermore, our results indicate that to achieve maximum enhancement of the permeability, the optimal treatment will depend on the exact lipid composition of the skin, as well as on the CAP source used.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.846
DOI: 10.1002/PPAP.201900122
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“Cerenkov emission of terahertz acoustic-phonons from graphene”. Zhao CX, Xu W, Peeters FM, Applied physics letters 102, 222101 (2013). http://doi.org/10.1063/1.4808392
Abstract: We present a theoretical study of the electrical generation of acoustic-phonon emission from graphene at room temperature. The drift velocity (v(x)) and temperature of electrons driven by dc electric field (F-x) are determined by solving self-consistently the momentum-and energy-balance equations derived from the Boltzmann equation. We find that in the presence of impurity, acoustic-and optic-phonon scattering, v(x) can be much larger than the longitudinal (v(l)) and transverse (v(t)) sound velocities in graphene even within the linear response regime. As a result, although the acoustic Cerenkov effect cannot be obviously seen in the analytical formulas, the enhanced acoustic-phonon emission can be observed with increasing F-x when v(x) > v(l) and v > v(t). The frequency of acoustic-phonon emission from graphene can be above 10 THz, which is much higher than that generated from conventional semiconductor systems. This study is pertinent to the application of graphene as hypersonic devices such as terahertz sound sources. (C) 2013 AIP Publishing LLC.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 25
DOI: 10.1063/1.4808392
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“CFD investigation of a multi-tube photocatalytic reactor in non-steady-state conditions”. van Walsem J, Verbruggen SW, Modde B, Lenaerts S, Denys S, Chemical engineering journal 304, 808 (2016). http://doi.org/10.1016/J.CEJ.2016.07.028
Abstract: A novel multi-tube photoreactor is presented with a high efficiency (over 90% conversion) toward the degradation of acetaldehyde in air under UV conditions with an incident intensity of 2.1 mW cm−2. A CFD model was developed to simulate the transient adsorption and photocatalytic degradation processes of acetaldehyde in this reactor design and to estimate the corresponding kinetic parameters through an optimization routine using the experimentally determined outlet concentration profiles. The CFD model takes into account the entire reactor geometry and all relevant flow parameters, in contrast to analytical methods that often oversimplify the physical and chemical process characteristics. Using CFD, we show that both adsorption and desorption rate constants increase by respectively one and two orders of magnitude when the UV light is switched on, which clearly affects the transient behavior. The agreement of the experimental and modelled concentration profiles is excellent as evidenced by a coefficient of determination of at least 0.965. To demonstrate the reliability and accuracy of all parameters obtained from the modelling approach, an ultimate validation test was performed using other conditions than the ones used for estimating the kinetic parameters. The model was able to accurately simulate simultaneous adsorption, desorption and photocatalytic degradation.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 6.216
Times cited: 10
DOI: 10.1016/J.CEJ.2016.07.028
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“CFD modeling of transient adsorption/desorption behavior in a gas phase photocatalytic fiber reactor”. Verbruggen SW, Keulemans M, van Walsem J, Tytgat T, Lenaerts S, Denys S, Chemical engineering journal 292, 42 (2016). http://doi.org/10.1016/J.CEJ.2016.02.014
Abstract: We present the use of computational fluid dynamics (CFD) for accurately determining the adsorption parameters of acetaldehyde on photocatalytic fiber filter material, integrated in a continuous flow system. Unlike the traditional analytical analysis based on Langmuir adsorption, not only steady-state situations but also transient phenomena can be accounted for. Air displacement effects in the reactor and gas detection cell are investigated and inherently made part of the model. Incorporation of a surface aldol condensation reaction in the CFD analysis further improves the accuracy of the model which enables to extract precise, intrinsic adsorption parameters for situations in which analytical analysis would otherwise fail.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 6.216
Times cited: 12
DOI: 10.1016/J.CEJ.2016.02.014
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“CFD modelling of small particle dispersion: the influence of the turbulence kinetic energy in the atmospheric boundary layer”. Gorlé, C, van Beeck J, Rambaud P, Van Tendeloo G, Atmospheric environment : an international journal 43, 673 (2009). http://doi.org/10.1016/j.atmosenv.2008.09.060
Abstract: When considering the modelling of small particle dispersion in the lower part of the Atmospheric Boundary Layer (ABL) using Reynolds Averaged Navier Stokes simulations, the particle paths depend on the velocity profile and on the turbulence kinetic energy, from which the fluctuating velocity components are derived to predict turbulent dispersion. It is therefore important to correctly reproduce the ABL, both for the velocity profile and the turbulence kinetic energy profile. For RANS simulations with the standard kå model, Richards and Hoxey (1993. Appropriate boundary conditions for computational wind engineering models using the kå turbulence model. Journal of Wind Engineering and Industrial Aerodynamics 4647, 145153.) proposed a set of boundary conditions which result in horizontally homogeneous profiles. The drawback of this method is that it assumes a constant profile of turbulence kinetic energy, which is not always consistent with field or wind tunnel measurements. Therefore, a method was developed which allows the modelling of a horizontally homogeneous turbulence kinetic energy profile that is varying with height. By comparing simulations performed with the proposed method to simulations performed with the boundary conditions described by Richards and Hoxey (1993. Appropriate boundary conditions for computational wind engineering models using the kå turbulence model. Journal of Wind Engineering and Industrial Aerodynamics 4647, 145153.), the influence of the turbulence kinetic energy on the dispersion of small particles over flat terrain is quantified.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.629
Times cited: 79
DOI: 10.1016/j.atmosenv.2008.09.060
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“CFD- and radiation field modeling of a gas phase photocatalytic multi-tube reactor”. Roegiers J, van Walsem J, Denys S, Chemical engineering journal 338, 287 (2018). http://doi.org/10.1016/J.CEJ.2018.01.047
Abstract: This paper focusses on the development of a Multiphysics model as a tool for assessing the performance of a multi-tube photoreactor. The model predicts the transient behavior of acetaldehyde concentration, as a model compound for the organic fraction of the indoor air pollutants, under varying sets of conditions. A 3D-model couples radiation field modeling with reaction kinetics and fluid dynamics in order to simulate the transport of the pollutant as it progresses through the reactor. A model-based approach is proposed to determine the layer thickness and refractive index of different P25-powder modified solgel coatings, using an optimization procedure to estimate these parameters based on UV-irradiance measurements. The radiation field model was able to accurately predict the irradiance on the catalytic surface within the reactor. Consequently, the radiation field model was used to define an irradiance dependent reaction rate constant in a coupled Multiphysics model. An optimization routine was deployed to estimate the adsorption, desorption- and photocatalytic reaction rate constants on the TiO2-surface, using experimentally determined, transient outlet concentrations of acetaldehyde. Additionally, a validation test was performed in an air-tight climate chamber at much higher flow rates, higher irradiance and realistic indoor pollutant concentrations to emphasize the reliability and accuracy of the parameters for adsorption, desorption and photocatalytic reaction. The developed model makes it possible to optimize the reactor design and scale-up for commercial applications.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1016/J.CEJ.2018.01.047
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Van Hoecke L (2024) CFD-Assisted design of fluidized reactors for H2 release from LOHC. XXXIII, 181 p
Abstract: Hydrogen (H2) is expected to become a key molecule in the transition towards a society running on renewable energy. It can be used to store excess renewable energy at peak production moments and release this energy at a later stage when renewable energy production is less. However, storing H2 is challenging due to the low density of this gas. As a solution, Liquid Organic Hydrogen Carriers or LOHC molecules have been proposed in the passed to increase volumetric energy density of H2. LOHC are a class of molecules that have storage sites available, to which the H2 gas can be chemically bounded. The LOHC molecule under investigation was dibenzyltoluene (DBT), which is an oil like liquid, that is easy to transport and poses little fire or explosion risks. To release the H2 from the DBT carrier, via a so-called dehydrogenation reaction, efficient mass and heat transfer is required during the process, since a large volume increase is expected from H2 release and the reaction is endothermic, i.e., a self – cooling process that takes place at temperatures around 300 C. The heat has to be supplied specifically to the active sites of catalyst particles that are present inside the reactor and which enable the dehydrogenation to proceed. For heat transfer limited processes fluidized bed reactors are often used, which is a type of reactor where the particle phase is being agitated by the fluid flow. The research proposed in this work, was to explore via computational fluid dynamics (CFD) simulations the possibilities and challenges of using fluidized bed reactors for the dehydrogenation of LOHC. The model selection required for CFD simulations of a three-phase system was investigated in this work, with a main emphasis on the drag model selection. The CFD modelling study was focused on the use of swirling fluidized bed reactors, since it was hypothesised that the swirling effect could also aid in increased removal of the gas phase from the reaction medium to increase the efficiency of the process. Ultimately, it was shown that the main challenges in the design of fluidized bed reactors will be to create uniform particle distribution inside the reactor. A new design for a dehydrogenation reactor is proposed based on the insights gained in this thesis.
Keywords: Doctoral thesis; Engineering sciences. Technology
DOI: 10.63028/10067/2056450151162165141
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“CFD-modelling of activated carbon fibers for indoor air purification”. Roegiers J, Denys S, Chemical engineering journal 365, 80 (2019). http://doi.org/10.1016/J.CEJ.2019.02.007
Abstract: Activated carbon fibers for indoor air purification were investigated by means of pressure drop and adsorption capacity. The Darcy-Forchheimer law combined with Computational Fluid Dynamics (CFD) modelling was deployed to simulate the pressure drop over an activated carbon fiber (ACF) filter with varying filter thickness. The CFD model was later combined with adsorption modelling to simulate breakthrough profiles of acetaldehyde adsorption on the ACF-filter. The adsorption model incorporates mass transfer resistance and adsorption equilibrium. It assumes local equilibrium between gas phase and solid phase. The latter was investigated for three different adsorption isotherms: linear, Langmuir and Freundlich adsorption. Successful agreement between model simulations and experimental data was obtained, using the Freundlich adsorption model. The numerical model could provide valuable insights and allows to continuously improve the design of filtration devices.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1016/J.CEJ.2019.02.007
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“CF4 decomposition in a low-pressure ICP : influence of applied power and O2 content”. Setareh M, Farnia M, Maghari A, Bogaerts A, Journal of physics: D: applied physics 47, 355205 (2014). http://doi.org/10.1088/0022-3727/47/35/355205
Abstract: This paper focuses on the investigation of CF4 decomposition in a low-pressure inductively coupled plasma by means of a global model. The influence of O2 on the CF4 decomposition process is studied for conditions used in semiconductor manufacturing processes. The model is applied for different powers and O2 contents ranging between 2% and 98% in the CF4/O2 gas mixture. The model includes the reaction mechanisms in the gas phase coupled with the surface reactions and sticking probabilities of the species at the walls. The calculation results are first compared with experimental results from the literature (for the electron density, temperature and F atom density) at a specific power, in the entire range of CF4/O2 gas mixture ratios, and the obtained agreements indicate the validity of the model. The main products of the gas mixture, obtained from this model, include CO, CO2 and COF2 together with a low fraction of F2. The most effective reactions for the formation and loss of the various species in this process are also determined in detail. Decomposition of CF4 produces mostly CF3 and F radicals. These radicals also contribute to the backward reactions, forming again CF4. This study reveals that the maximum decomposition efficiency of CF4 is achieved at a CF4/O2 ratio equal to 1, at the applied power of 300 W.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.588
Times cited: 8
DOI: 10.1088/0022-3727/47/35/355205
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“Chabazite : stable cation-exchanger in hyper alkaline concrete pore water”. Van Tendeloo L, Wangermez W, Kurttepeli M, de Blochouse B, Bals S, Van Tendeloo G, Martens JA, Maes A, Kirschhock CEA, Breynaert E, Environmental science and technology 49, 2358 (2015). http://doi.org/10.1021/es505346j
Abstract: To avoid impact on the environment, facilities for permanent disposal of hazardous waste adopt multibarrier design schemes. As the primary barrier very often consists of cement-based materials, two distinct aspects are essential for the selection of suitable complementary barriers: (1) selective sorption of the contaminants in the repository and (2) long-term chemical stability in hyperalkaline concrete-derived media. A multidisciplinary approach combining experimental strategies from environmental chemistry and materials science is therefore essential to provide a reliable assessment of potential candidate materials. Chabazite is typically synthesized in 1 M KOH solutions but also crystallizes in simulated young cement pore water, a pH 13 aqueous solution mainly containing K+ and Na+ cations. Its formation and stability in this medium was evaluated as a function of temperature (60 and 85 °C) over a timeframe of more than 2 years and was also asessed from a mechanistic point of view. Chabazite demonstrates excellent cation-exchange properties in simulated young cement pore water. Comparison of its Cs+ cation exchange properties at pH 8 and pH 13 unexpectedly demonstrated an increase of the KD with increasing pH. The combined results identify chabazite as a valid candidate for inclusion in engineered barriers for concrete-based waste disposal.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 6.198
Times cited: 13
DOI: 10.1021/es505346j
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“Chainlike transitions in Wigner crystals : sequential versus nonsequential”. Galvan-Moya, Misko VR, Peeters FM, Physical review : B : condensed matter and materials physics 92, 064112 (2015). http://doi.org/10.1103/PhysRevB.92.064112
Abstract: The structural transitions of the ground state of a system of repulsively interacting particles confined in a quasi-one-dimensional channel, and the effect of the interparticle interaction as well as the functional form of the confinement potential on those transitions are investigated. Although the nonsequential ordering of transitions (non-SOT), i.e., the 1 – 2 – 4 – 3 – 4 – 5 – 6 – ... sequence of chain configurations with increasing density, is widely robust as predicted in a number of theoretical studies, the sequential ordering of transitions (SOT), i.e., the 1 – 2 – 3 – 4 – 5 – 6 – ... chain, is found as the ground state for long-ranged interparticle interaction and hard-wall-like confinement potentials. We found an energy barrier between every two different phases around its transition point, which plays an important role in the preference of the system to follow either a SOT or a non-SOT. However, that preferential transition requires also the stability of the phases during the transition. Additionally, we analyze the effect of a small structural disorder on the transition between the two phases around its transition point. Our results show that a small deformation of the triangular structure changes dramatically the picture of the transition between two phases, removing in a considerable region the non-SOT in the system. This feature could explain the fact that the non-SOT is, up to now, not observed in experimental systems, and suggests a more advanced experimental setup to detect the non-SOT.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 3
DOI: 10.1103/PhysRevB.92.064112
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“Challenges in the electrochemical (bio)sensing of non-electroactive food and environmental contaminants”. Moro G, De Wael K, Moretto LM, Current opinion in electrochemistry 16, 57 (2019). http://doi.org/10.1016/J.COELEC.2019.04.019
Abstract: The electrochemical detection of non-electroactive contaminants can be successfully faced via the use of indirect detection strategies. These strategies can provide sensitive and selective responses often coupled with portable and user-friendly analytical tools. Indirect detection strategies are usually based on the change in the signal of an electroactive probe, induced by the presence of the target molecule at a modified electrode. This critical review aims at addressing the developments in indirect electro-sensing strategies for non-electroactive contaminants in food and environmental analysis in the last years (2017-2019). Emphasis is given to the strategy design, the electrode modifiers used and the feasibility of technological transfer.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Times cited: 4
DOI: 10.1016/J.COELEC.2019.04.019
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Van Hoecke L, Laffineur L, Campe R, Perreault P, Verbruggen SW, Lenaerts S (2021) Challenges in the use of hydrogen for maritime applications
Abstract: Maritime shipping is a key factor that enables the global economy, however the pressure it exerts on the environment is increasing rapidly. In order to reduce the emissions of harmful greenhouse gasses, the search is on for alternative fuels for the maritime shipping industry. In this work the usefulness of hydrogen and hydrogen carriers is being investigated as a fuel for sea going ships. Due to the low volumetric energy density of hydrogen under standard conditions, the need for efficient storage of this fuel is high. Key processes in the use of hydrogen are discussed, starting with the production of hydrogen from fossil and renewable sources. The focus of this review is different storage methods, and in this work we discuss the storage of hydrogen at high pressure, in liquefied form at cryogenic temperatures and bound to liquid or solid-state carriers. In this work a theoretical introduction to different hydrogen storage methods precedes an analysis of the energy-efficiency and practical storage density of the carriers. In the final section the major challenges and hurdles for the development of hydrogen storage for the maritime industry are discussed. The most likely challenges will be the development of a new bunkering infrastructure and suitable monitoring of the safety to ensure safe operation of these hydrogen carriers on board the ship.
Keywords: A1 Journal Article;Review article, Hydrogen Production, Hydrogen Storage, Maritime Applications; Sustainable energy, air and water technology (DuEL)
Impact Factor: 29.518
DOI: 10.1039/D0EE01545H
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“Challenges in unconventional catalysis”. Bogaerts A, Centi G, Hessel V, Rebrov E, Catalysis today 420, 114180 (2023). http://doi.org/10.1016/j.cattod.2023.114180
Abstract: Catalysis science and technology increased efforts recently to progress beyond conventional “thermal” catalysis and face the challenges of net-zero emissions and electrification of production. Nevertheless, a better gaps and opportunities analysis is necessary. This review analyses four emerging areas of unconventional or less- conventional catalysis which share the common aspect of using directly renewable energy sources: (i) plasma catalysis, (ii) catalysis for flow chemistry and process intensification, (iii) application of electromagnetic (EM) fields to modulate catalytic activity and (iv) nanoscale generation at the catalyst interface of a strong local EM by plasmonic effect. Plasma catalysis has demonstrated synergistic effects, where the outcome is higher than the sum of both processes alone. Still, the underlying mechanisms are complex, and synergy is not always obtained. There is a crucial need for a better understanding to (i) design catalysts tailored to the plasma environment, (ii) design plasma reactors with optimal transport of plasma species to the catalyst surface, and (iii) tune the plasma conditions so they work in optimal synergy with the catalyst. Microfluidic reactors (flow chemistry) is another emerging sector leading to the intensification of catalytic syntheses, particularly in organic chemistry. New unconventional catalysts must be designed to exploit in full the novel possibilities. With a focus on (a) continuous-flow photocatalysis, (b) electrochemical flow catalysis, (c) microwave flow catalysis and (d) ultra sound flow activation, a series of examples are discussed, with also indications on scale-up and process indus trialisation. The third area discussed regards the effect on catalytic performances of applying oriented EM fields spanning several orders of magnitude. Under well-defined conditions, gas breakdown and, in some cases, plasma formation generates activated gas phase species. The EM field-driven chemical conversion processes depend further on structured electric/magnetic catalysts, which shape the EM field in strength and direction. Different effects influencing chemical conversion have been reported, including reduced activation energy, surface charging, hot spot generation, and selective local heating. The last topic discussed is complementary to the third, focusing on the possibility of tuning the photo- and electro-catalytic properties by creating a strong localised electrical field with a plasmonic effect. The novel possibilities of hot carriers generated by the plasmonic effect are also discussed. This review thus aims to stimulate the reader to make new, creative catalysis to address the challenges of reaching a carbon-neutral world.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 5.3
DOI: 10.1016/j.cattod.2023.114180
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“Change in silica sources in Roman and post Roman glass”. Aerts A, Janssens K, Velde B, Dijkman W, Spectrochimica acta: part B : atomic spectroscopy 58, 659 (2003). http://doi.org/10.1016/S0584-8547(02)00287-2
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 3.241
DOI: 10.1016/S0584-8547(02)00287-2
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“Change in upper airway geometry between upright and supine position during tidal nasal breathing”. Van Holsbeke CS, Verhulst SL, Vos WG, de Backer JW, Vinchurkar SC, Verdonck PR, van Doorn JWD, Nadjmi N, de Backer WA, Journal Of Aerosol Medicine And Pulmonary Drug Delivery 27, 51 (2014). http://doi.org/10.1089/jamp.2012.1010
Keywords: A1 Journal article; Biophysics and Biomedical Physics; Condensed Matter Theory (CMT); Laboratory Experimental Medicine and Pediatrics (LEMP); Translational Neurosciences (TNW)
Impact Factor: 2.528
Times cited: 16
DOI: 10.1089/jamp.2012.1010
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“Changing chirality during single-walled carbon nanotube growth : a reactive molecular dynamics/Monte Carlo study”. Neyts EC, van Duin ACT, Bogaerts A, Journal of the American Chemical Society 133, 17225 (2011). http://doi.org/10.1021/ja204023c
Abstract: The growth mechanism and chirality formation of a single-walled carbon nanotube (SWNT) on a surface-bound nickel nanocluster are investigated by hybrid reactive molecular dynamics/force-biased Monte Carlo simulations. The validity of the interatomic potential used, the so-called ReaxFF potential, for simulating catalytic SWNT growth is demonstrated. The SWNT growth process was found to be in agreement with previous studies and observed to proceed through a number of distinct steps, viz., the dissolution of carbon in the metallic particle, the surface segregation of carbon with the formation of aggregated carbon clusters on the surface, the formation of graphitic islands that grow into SWNT caps, and finally continued growth of the SWNT. Moreover, it is clearly illustrated in the present study that during the growth process, the carbon network is continuously restructured by a metal-mediated process, thereby healing many topological defects. It is also found that a cap can nucleate and disappear again, which was not observed in previous simulations. Encapsulation of the nanoparticle is observed to be prevented by the carbon network migrating as a whole over the cluster surface. Finally, for the first time, the chirality of the growing SWNT cap is observed to change from (11,0) over (9,3) to (7,7). It is demonstrated that this change in chirality is due to the metal-mediated restructuring process.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 13.858
Times cited: 116
DOI: 10.1021/ja204023c
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“Characterisation of a high-power impulse magnetron sputtered C/Mo/W wear resistant coating by transmission electron microscopy”. Sharp J, Mueller IC, Mandal P, Abbas A, Nord M, Doye A, Ehiasarian A, Hovsepian P, MacLaren I, Rainforth WM, Surface and coatings technology 377, 124853 (2019). http://doi.org/10.1016/J.SURFCOAT.2019.08.007
Abstract: Thin films of C/Mo/W deposited using combined UBM/HIPIMS sputtering show 2-8 nm clusters of material richer in Mo and W than the matrix (found by EDS microanalysis), with structures that resemble graphitic onions with the metal atoms arranged regularly within them. EELS microanalysis showed the clusters to be rich in W and Mo. As the time averaged power used in the pulsed HIPIMS magnetron was increased, the clusters became more defined, larger, and arranged into layers with amorphous matrix between them. Films deposited with average HIPIMS powers of 4 kW and 6 kW also showed a periodic modulation of the cluster density within the finer layers giving secondary, wider stripes in TEM. By analysing the ratio between the finer and coarser layers, it was found that this meta-layering is related to the substrate rotation in the deposition chamber but in a non-straightforward way. Reasons for this are proposed. The detailed structure of the clusters remains unknown and is the subject of further work. Fluctuation electron microscopy results indicated the presence of crystal planes with the graphite interlayer spacing, crystal planes in hexagonal WC perpendicular to the basal plane, and some plane spacings found in Mo2C. Other peaks in the FEM results suggested symmetry-related starting points for future determination of the structure of the clusters.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.589
Times cited: 1
DOI: 10.1016/J.SURFCOAT.2019.08.007
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