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“Resonant tunneling through S- and U-shaped graphene nanoribbons”. Zhang ZZ, Wu ZH, Chang K, Peeters FM, Nanotechnology 20, 415203 (2009). http://doi.org/10.1088/0957-4484/20/41/415203
Abstract: We theoretically investigate resonant tunneling through S- and U-shaped nanostructured graphene nanoribbons. A rich structure of resonant tunneling peaks is found emanating from different quasi-bound states in the middle region. The tunneling current can be turned on and off by varying the Fermi energy. Tunability of resonant tunneling is realized by changing the width of the left and/or right leads and without the use of any external gates.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.44
Times cited: 32
DOI: 10.1088/0957-4484/20/41/415203
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“Resonant tunnelling through D- states”. Lok JGS, Geim AK, Maan JC, Marmorkos I, Peeters FM, Mori N, Eaves L, McDonnell P, Henini M, Sakai JW, Main PC;, Surface science : a journal devoted to the physics and chemistry of interfaces
T2 –, 11th International Conference on the Electronic Properties of 2-Dimensional Systems (EP2DS XI), August 07-11, 1995, Univ. Nottingham, Nottingham, England 362, 247 (1996). http://doi.org/10.1016/0039-6028(96)00395-0
Abstract: We have studied tunnelling through Si donors incorporated in the quantum well of double barrier resonant tunnelling devices. In addition to a resonance associated with the ground state of a single donor (1s level), a novel donor-related resonance at a smaller binding energy is observed in high magnetic fields where it becomes dominant over the Is resonance. We attribute this novel feature to a D-minus state of a shallow donor.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.925
DOI: 10.1016/0039-6028(96)00395-0
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“Resonant valley filtering of massive Dirac electrons”. Moldovan D, Masir MR, Covaci L, Peeters FM, Physical review : B : condensed matter and materials physics 86, 115431 (2012). http://doi.org/10.1103/PhysRevB.86.115431
Abstract: Electrons in graphene, in addition to their spin, have two pseudospin degrees of freedom: sublattice and valley pseudospin. Valleytronics uses the valley degree of freedom as a carrier of information similarly to the way spintronics uses electron spin. We show how a double-barrier structure consisting of electric and vector potentials can be used to filter massive Dirac electrons based on their valley index. We study the resonant transmission through a finite number of barriers and we obtain the energy spectrum of a superlattice consisting of electric and vector potentials. When a mass term is included, the energy bands and energy gaps at the K and K′ points are different and they can be tuned by changing the potential.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 55
DOI: 10.1103/PhysRevB.86.115431
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“Resource effectiveness of the European automotive sector : a statistical entropy analysis over time”. Parchomenko A, Nelen D, Gillabel J, Vrancken KCM, Rechberger H, Resources Conservation And Recycling 169, 105558 (2021). http://doi.org/10.1016/J.RESCONREC.2021.105558
Abstract: The European automotive sector is faced with potentially disruptive challenges. In particular, the projected increase in the share of electric vehicles (EVs) and calls to prepare for the implementation of more circular economy (CE) strategies are increasingly demanding systemic adaptations. Given the goals of the CE, the adaptations should enable a maximal preservation of the function and value of products (e.g. extension of lifetime), components (e.g. reuse of parts) and materials (e.g., material recycling), thus saving on the energy, materials and effort that would be required to restore the lost functionalities. In this context, statistical entropy analysis (SEA) is proposed as a methodology to assess the effort needed for preserving and restoring functionality at different product, component and material life cycle stages. Effort is measured as changes in statistical entropy that are caused by concentration and dilution activities in the production – consumption – End-of-Life (EoL) system. SEA was applied to a generic model of the European automotive system, in combination with a stock-driven model and a material flow analysis (MFA), allowing statistical entropy changes to be projected over time. The paper demonstrates how SEA can facilitate decision making on the transition towards a more circular economy by quantifying the effects of particular CE strategies and their combinations. The results show that without any additional system adaptations, an increasing share of EVs towards the year 2050 will lead to substantially increased effort in production as well as end-of-life vehicle treatment.
Keywords: A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 3.313
DOI: 10.1016/J.RESCONREC.2021.105558
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“Resource recovery from pig manure via an integrated approach : a technical and economic assessment for full-scale applications”. De Vrieze J, Colica G, Pintucci C, Sarli J, Pedizzi C, Willeghems G, Bral A, Varga S, Prat D, Peng L, Spiller M, Buysse J, Colsen J, Benito O, Carballa M, Vlaeminck SE, Bioresource technology 272, 582 (2019). http://doi.org/10.1016/J.BIORTECH.2018.10.024
Abstract: Intensive livestock farming cannot be uncoupled from the massive production of manure, requiring adequate management to avoid environmental damage. The high carbon, nitrogen and phosphorus content of pig manure enables targeted resource recovery. Here, fifteen integrated scenarios for recovery of water, nutrients and energy are compared in terms of technical feasibility and economic viability. The recovery of refined nutrients with a higher market value and quality, i.e., (NH4)2SO4 for N and struvite for P, coincided with higher net costs, compared to basic composting. The inclusion of anaerobic digestion promoted nutrient recovery efficiency, and enabled energy recovery through electricity production. Co-digestion of the manure with carbon-rich waste streams increased electricity production, but did not result in lower process costs. Overall, key drivers for the selection of the optimal manure treatment scenario will include the market demand for more refined (vs. separated or concentrated) products, and the need for renewable electricity production.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1016/J.BIORTECH.2018.10.024
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Van Tendeloo M (2022) Resource-efficient nitrogen removal from sewage : kinetic, physical and chemical tools for mainstream partial nitritation/anammox. iv, 204 p
Abstract: Adequate removal of pollutants from sewage is important to protect the environment and public health. Today, sewage treatment plants are operational in many parts of the world, and although the used technologies are effective in removing pollutants from wastewater, they are energy- and resource-intensive. Reshaping sewage treatment into a two-stage system, with separated organic carbon and nitrogen removal, facilitates the transformation towards energy-positive sewage treatment. This thesis will focus on resource-efficient nitrogen removal from sewage via partial nitritation/anammox (PN/A), with reduced organic carbon and oxygen consumption compared to conventional techniques. PN/A relies on the teamwork between two microbial groups to convert ammonium into nitrogen gas. Several other groups of microbes however can proliferate in the sludge, competing for substrate with the key players, lowering the nitrogen removal efficiency and increasing the energy demand. To obtain the desired microbial community, control tools should be applied to selectively promote the desired microbes while suppressing the unwanted competitors. In this thesis, multiple control tools were studied to establish a workable framework for successful implementation of PN/A in the main stream of a sewage treatment plant. These tools can be divided into three categories: i) kinetic tools, regulating substrate availability (e.g., oxygen availability control and residual ammonium concentration), ii) physical tools, revolving around sludge retention and selection (e.g., sludge age control and sludge aggregation form), and iii) chemical tools, exposing the sludge to stress conditions for which the unwanted microbes are vulnerable (e.g., sludge treatments with a single stressor such as free ammonia). The first research chapter focussed on oxygen availability control and single-stressor sludge treatments. The following two chapters covered the development of a novel multi-stressor concept combining substrate starvation and exposure to sulphide and free ammonia. In the final research chapter, the previously obtained knowledge was combined into a demonstration study on pilot-scale. The combination of these control tools was found effective in achieving nitrogen removal via PN/A, both on lab- and pilot-scale. Consequently, the obtained results in this thesis can catalyse the implementation of mainstream PN/A by providing a toolbox with multiple control tools and clever reactor design, thus advancing the concept of energy neutrality and resource efficiency in sewage treatment plants.
Keywords: Doctoral thesis; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
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“Response function of a Hall magnetosensor in the diffusive regime”. Cornelissens YG, Peeters FM, Journal of applied physics 92, 2006 (2002). http://doi.org/10.1063/1.1487909
Abstract: Two-dimensional electron gas systems patterned into micrometer Hall bars can be used as Hall magnetosensors. In this way, ballistic Hall probes have already been studied and used successfully. Here, the response function of a Hall sensor is determined in the diffusive regime, which allows this device to be used as a magnetosensor for the determination of inhomogeneous magnetic field distributions. Furthermore, the influence of the geometry of the Hall bar on this response function, such as circular corners and asymmetry in the probes, is also investigated and appears to be non-negligible. (C) 2002 American Institute of Physics.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.068
Times cited: 24
DOI: 10.1063/1.1487909
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“Restoration of X-ray fluorescence images of hidden paintings”. Anitha A, Brasoveanu A, Duarte M, Hughes S, Daubechies I, Dik J, Janssens K, Alfeld M, Signal processing 93, 592 (2013). http://doi.org/10.1016/J.SIGPRO.2012.09.027
Abstract: This paper describes our methods for repairing and restoring images of hidden paintings (paintings that have been painted over and are now covered by a new surface painting) that have been obtained via noninvasive X-ray fluorescence imaging of their canvases. This recently developed imaging technique measures the concentrations of various chemical elements at each two-dimensional spatial location across the canvas. These concentrations in turn result from pigments present both in the surface painting and in the hidden painting beneath. These X-ray fluorescence images provide the best available data from which to noninvasively study a hidden painting. However, they are typically marred by artifacts of the imaging process, features of the surface painting, and areas of information loss. Repairing and restoring these images thus consists of three stages: (1) repairing acquisition artifacts in the dataset, (2) removal of features in the images that result from the surface painting rather than the hidden painting, and (3) identification and repair of areas of information loss. We describe methods we have developed to address each of these stages: a total-variation minimization approach to artifact correction, a novel method for underdetermined blind source separation with multimodal side information to address surface feature removal, and two application-specific new methods for automatically identifying particularly thick or X-ray absorbent surface features in the painting. Finally, we demonstrate the results of our methods on a hidden painting by the artist Vincent van Gogh. (C) 2012 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 3.11
Times cited: 13
DOI: 10.1016/J.SIGPRO.2012.09.027
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“Restructuring of titanium oxide overlayers over nickel nanoparticles during catalysis”. Monai M, Jenkinson K, Melcherts AEM, Louwen JN, Irmak EA, Van Aert S, Altantzis T, Vogt C, van der Stam W, Duchon T, Smid B, Groeneveld E, Berben P, Bals S, Weckhuysen BM, Science 380, 644 (2023). http://doi.org/10.1126/SCIENCE.ADF6984
Abstract: Reducible supports can affect the performance of metal catalysts by the formation of suboxide overlayers upon reduction, a process referred to as the strong metal-support interaction (SMSI). A combination of operando electron microscopy and vibrational spectroscopy revealed that thin TiOx overlayers formed on nickel/titanium dioxide catalysts during 400 degrees C reduction were completely removed under carbon dioxide hydrogenation conditions. Conversely, after 600 degrees C reduction, exposure to carbon dioxide hydrogenation reaction conditions led to only partial reexposure of nickel, forming interfacial sites in contact with TiOx and favoring carbon-carbon coupling by providing a carbon species reservoir. Our findings challenge the conventional understanding of SMSIs and call for more-detailed operando investigations of nanocatalysts at the single-particle level to revisit static models of structure-activity relationships.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Applied Electrochemistry & Catalysis (ELCAT)
Impact Factor: 56.9
Times cited: 29
DOI: 10.1126/SCIENCE.ADF6984
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“Rethinking resilient agriculture : from Climate-Smart Agriculture to Vulnerable-Smart Agriculture”. Azadi H, Moghaddam SM, Burkart S, Mahmoudi H, Van Passel S, Kurban A, Lopez-Carr D, Journal Of Cleaner Production 319, 128602 (2021). http://doi.org/10.1016/J.JCLEPRO.2021.128602
Abstract: Climate-Smart Agriculture (CSA) is seeking to overcome the food security problem and develop rural livelihoods while minimizing negative impacts on the environment. However, when such synergies exist, the situation of small-scale farmers is often overlooked, and they are unable to implement new practices and technologies. Therefore, the main aim of this study is to improve CSA by adding the neglected but very important element “small-scale farmer”, and introduce Vulnerable-Smart Agriculture (VSA) as a complete version of CSA. VSA indicates, based on the results of this study, that none of the decisions made by policymakers can be realistic and functional as long as the voice of the farmers influenced by their decisions is not heard. Therefore, to identify different levels for possible interventions and develop VSA monitoring indicators, a new conceptual framework needs to be developed. This study proposed such a framework consisting of five elements: prediction of critical incidents by farmers, measuring the consequences of incidents, identifying farmers' coping strategies, assessing farmers' livelihood capital when facing an incident, and adapting to climate incidents. The primary focus of this study is on farmers' learning and operational preparation to deal with tension and disasters at farm level. Understanding the implications of threats from climate change and the recognizing of coping mechanisms will contribute to an increase in understanding sustainable management.
Keywords: A1 Journal article; Engineering sciences. Technology; Engineering Management (ENM)
Impact Factor: 5.715
DOI: 10.1016/J.JCLEPRO.2021.128602
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“Return-sludge treatment with endogenous free nitrous acid limits nitrate production and N₂O emission for mainstream partial nitritation/anammox”. Peng L, Xie Y, Van Beeck W, Zhu W, Van Tendeloo M, Tytgat T, Lebeer S, Vlaeminck SE, Environmental Science &, Technology 54, 5822 (2020). http://doi.org/10.1021/ACS.EST.9B06404
Abstract: Nitrite oxidizing bacteria (NOB) and nitrous oxide (N2O) hinder the development of mainstream partial nitritation/anammox. To overcome these, endogenous free ammonia (FA) and free nitrous acid (FNA), which can be produced in the sidestream, were used for return-sludge treatment for two integrated-film activated sludge reactors containing biomass in flocs and on carriers. The repeated exposure of biomass from one reactor to FA shocks had a limited impact on NOB suppression but inhibited anammox bacteria (AnAOB). In the other reactor, repeated FNA shocks to the separated flocs failed to limit the system’s nitrate production since NOB activity was still high on the biofilms attached to the unexposed carriers. In contrast, the repeated FNA treatment of flocs and carriers favored aerobic ammonium-oxidizing bacteria (AerAOB) over NOB activity with AnAOB negligibly affected. It was further revealed that return-sludge treatment with higher FNA levels led to lower N2O emissions under similar effluent nitrite concentrations. On this basis, weekly 4 h FNA shocks of 2.0 mg of HNO2-N/L were identified as an optimal and realistic treatment, which not only enabled nitrogen removal efficiencies of ∼65% at nitrogen removal rates of ∼130 mg of N/L/d (20 °C) but also yielded the lowest cost and carbon footprint.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 11.4
Times cited: 1
DOI: 10.1021/ACS.EST.9B06404
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“Revealing hidden paint layers in oil paintings by means of scanning macro-XRF : a mock-up study based on Rembrandt's “An old man in military costume””. Alfeld M, de Nolf W, Cagno S, Janssens K, et al, Journal of analytical atomic spectrometry 28, 40 (2013). http://doi.org/10.1039/C2JA30119A
Abstract: Over the past several decades the oeuvre of Rembrandt has been the subject of extensive art historical and scientific investigations. One of the most striking features to emerge is his frequent re-use of canvases and panels. The painting An Old Man in Military Costume (78.PB.246), in the collection of the J. Paul Getty Museum, is an example of such a re-used panel. Conventional imaging techniques revealed the presence of a second portrait under the surface portrait, but the details of this hidden portrait have not yet been revealed. Vermilion (HgS) has been identified to have been used nearly exclusively in the flesh tones of the lower painting, suggesting that element-specific XRF imaging might successfully image the hidden portrait. To test this hypothesis, a full-scale mock-up of the painting was created, including a “free impression” of the hidden portrait, reproducing as closely as possible the pigments and paint stratigraphy of the original painting. XRF imaging of the mock-up painting was conducted using three different XRF imaging systems: a mobile X-ray tube based system and two synchrotron-based setups (one equipped with multiple SDDs and one equipped with a Maia detector). The sensitivity, limits of detection and imaging capabilities of each system under the chosen experimental conditions are evaluated and compared. The results indicate that an investigation of the original painting by this method would have an excellent chance of success.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 3.379
DOI: 10.1039/C2JA30119A
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“Revealing pH-Dependent Activities and Surface Instabilities for Ni-Based Electrocatalysts during the Oxygen Evolution Reaction”. Yang C, Batuk M, Jacquet Q, Rousse G, Yin W, Zhang L, Hadermann J, Abakumov AM, Cibin G, Chadwick A, Tarascon J-M, Grimaud A, ACS energy letters , 2884 (2018). http://doi.org/10.1021/acsenergylett.8b01818
Abstract: Multiple electrochemical processes are involved at the catalyst/ electrolyte interface during the oxygen evolution reaction (OER). With the purpose of elucidating the complexity of surface dynamics upon OER, we systematically studied two Ni-based crystalline oxides (LaNiO3−δ and La2Li0.5Ni0.5O4) and compared them with the state-of-the-art Ni−Fe (oxy)- hydroxide amorphous catalyst. Electrochemical measurements such as rotating ring disk electrode (RRDE) and electrochemical quartz microbalance microscopy (EQCM) coupled with a series of physical characterizations including transmission electron microscopy (TEM) and X-ray absorption spectroscopy (XAS) were conducted to unravel the exact pH effect on both the OER activity and the catalyst stability. We demonstrate that for Ni-based crystalline catalysts the rate for surface degradation depends on the pH and is greater than the rate for surface reconstruction. This behavior is unlike that for the amorphous Ni oxyhydroxide catalyst, which is found to be more stable and pH-independent.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
DOI: 10.1021/acsenergylett.8b01818
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“Revealing the arc dynamics in a gliding arc plasmatron: a better insight to improve CO2conversion”. Ramakers M, Medrano JA, Trenchev G, Gallucci F, Bogaerts A, Plasma sources science and technology 26, 125002 (2017). http://doi.org/10.1088/1361-6595/aa9531
Abstract: A gliding arc plasmatron (GAP) is very promising for CO2 conversion into value-added chemicals, but to further improve this important application, a better understanding of the arc behavior is indispensable. Therefore, we study here for the first time the dynamic arc behavior of the GAP by means of a high-speed camera, for different reactor configurations and in a wide range of operating conditions. This allows us to provide a complete image of the behavior of the gliding arc. More specifically, the arc body shape, diameter, movement and rotation speed are analyzed and discussed. Clearly, the arc movement and shape relies on a number of factors, such as gas turbulence, outlet diameter, electrode surface, gas contraction and buoyance force. Furthermore, we also compare the experimentally measured arc movement to a state-of-the-art 3D-plasma model, which predicts the plasma movement and rotation speed with very good accuracy, to gain further insight in the underlying mechanisms. Finally, we correlate the arc dynamics with the CO2 conversion and energy efficiency, at exactly the same conditions, to explain the effect of these parameters on the CO2 conversion process. This work is important for understanding and optimizing the GAP for CO2 conversion.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.302
Times cited: 7
DOI: 10.1088/1361-6595/aa9531
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“Revealing the distribution of metal carboxylates in oil paint from the micro- to nanoscale”. Ma X, Beltran V, Ramer G, Pavlidis G, Parkinson DY, Thoury M, Meldrum T, Centrone A, Berrie BH, Angewandte Chemie: international edition in English 58, 11652 (2019). http://doi.org/10.1002/ANIE.201903553
Abstract: Oil paints comprise pigments, drying oils, and additives that together confer desirable properties, but can react to form metal carboxylates (soaps) that may damage artworks over time. To obtain information on soap formation and aggregation, we introduce a new tapping-mode measurement paradigm for the photothermal induced resonance (PTIR) technique that enables nanoscale IR spectroscopy and imaging on highly heterogenous and rough paint thin sections. PTIR is used in combination with mu-computed tomography and IR microscopy to determine the distribution of metal carboxylates in a 23-year old oil paint of known formulation. Results show that heterogeneous agglomerates of Al-stearate and a Zn-carboxylate complex with Zn-stearate nano-aggregates in proximity are distributed randomly in the paint. The gradients of zinc carboxylates are unrelated to the Al-stearate distribution. These measurements open a new chemically sensitive nanoscale observation window on the distribution of metal soaps that can bring insights for understanding soap formation in oil paint.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1002/ANIE.201903553
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“Reversible Clustering of Gold Nanoparticles under Confinement”. Sánchez-Iglesias A, Claes N, Solís DM, Taboada JM, Bals S, Liz-Marzán LM, Grzelczak M, Angewandte Chemie: international edition in English 57, 3183 (2018). http://doi.org/10.1002/anie.201800736
Abstract: A limiting factor of solvent-induced nanoparticle self-assembly is the need for constant sample dilution in assembly/disassembly cycles. Changes in the nanoparticle concentration alter the kinetics of the subsequent assembly process, limiting optical signal recovery. Herein, we show that upon confining hydrophobic nanoparticles in permeable silica nanocapsules, the number of nanoparticles participating in cyclic aggregation remains constant despite bulk changes in solution, leading to highly reproducible plasmon band shifts at different solvent compositions.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 11.994
Times cited: 53
DOI: 10.1002/anie.201800736
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“Reversible Li-intercalation through oxygen reactivity in Li-rich Li-Fe-Te oxide materials”. McCalla E, Prakash AS, Berg E, Saubanere M, Abakumov AM, Foix D, Klobes B, Sougrati MT, Rousse G, Lepoivre F, Mariyappan S, Doublet ML, Gonbeau D, Novak P, Van Tendeloo G, Hermann RP, Tarascon JM;, Journal of the electrochemical society 162, A1341 (2015). http://doi.org/10.1149/2.0991507jes
Abstract: Lithium-rich oxides are a promising class of positive electrode materials for next generation lithium-ion batteries, and oxygen plays a prominent role during electrochemical cycling either by forming peroxo-like species and/or by irreversibly forming oxygen gas during first charge. Here, we present Li-Fe-Te-O materials which show a tremendous amount of oxygen gas release. This oxygen release accounts for nearly all the capacity during the first charge and results in vacancies as seen by transmission electron microscopy. There is no oxidation of either metal during charge but significant changes in their environments. These changes are particularly extreme for tellurium. XRD and neutron powder diffraction both show limited Changes during cycling and no appreciable change in lattice parameters. A density functional theory study of this material is performed and demonstrates that the holes created on some of the oxygen atoms upon oxidation are partially stabilized through the formation of shorter O-O bonds, i.e. (O-2)(n-) species which on further delithiation show a spontaneous O-2 de-coordination from the cationic network and migration to the now empty lithium layer. The rate limiting step during charge is undoubtedly the diffusion of oxygen either out along the lithium layer or via columns of oxygen atoms. (C) 2015 The Electrochemical Society. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.259
Times cited: 23
DOI: 10.1149/2.0991507jes
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“Reversible ratchet effects in a narrow superconducting ring”. Jiang J, Wang Y-L, Milošević, MV, Xiao Z-L, Peeters FM, Chen Q-H, Physical Review B 103, 014502 (2021). http://doi.org/10.1103/PHYSREVB.103.014502
Abstract: We study the ratchet effect in a narrow pinning-free superconductive ring based on time-dependent Ginzburg-Landau (TDGL) equations. Voltage responses to external dc and ac currents at various magnetic fields are studied. Due to asymmetric barriers for flux penetration and flux exit in the ring-shaped superconductor, the critical current above which the flux-flow state is reached, as well as the critical current for the transition to the normal state, are different for the two directions of applied current. These effects cooperatively cause ratchet signal reversal at high magnetic fields, which has not been reported to date in a pinning-free system. The ratchet signal found here is larger than those induced by asymmetric pinning potentials. Our results also demonstrate the feasibility of using mesoscopic superconductors to employ a superconducting diode effect in versatile superconducting devices.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 4
DOI: 10.1103/PHYSREVB.103.014502
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“Reversible structural transition in nanoconfined ice”. Satarifard V, Mousaei M, Hadadi F, Dix J, Sobrino Fernández M, Carbone P, Beheshtian J, Peeters FM, Neek-Amal M, Physical review B 95, 064105 (2017). http://doi.org/10.1103/PHYSREVB.95.064105
Abstract: The report on square ice sandwiched between two graphene layers by Algara-Siller et al. [Nature (London) 519, 443 (2015)] has generated a large interest in this system. By applying high lateral pressure on nanoconfined water, we found that monolayer ice is transformed to bilayer ice when the two graphene layers are separated by H = 6,7 angstrom. It was also found that three layers of a denser phase of ice with smaller lattice constant are formed if we start from bilayer ice and apply a lateral pressure of about 0.7 GPa with H = 8,9 angstrom. The lattice constant (2.5-2.6 angstrom) in both transitions is found to be smaller than those typical for the known phases of ice and water, i.e., 2.8 angstrom. We validate these results using ab initio calculations and find good agreement between ab initio O-O distance and those obtained from classical molecular dynamics simulations. The reversibility of the mentioned transitions is confirmed by decompressing the systems.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 23
DOI: 10.1103/PHYSREVB.95.064105
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“Review of phonon behaviour and microstructural development leading to martensitic transformations in NixAl100-x alloys”. Tanner LE, Shapiro SM, Schryvers D, Noda Y, Shape memory materials and phenomena: fundamental aspects and applications 246, 265 (1992)
Keywords: A3 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 4
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“Reweighted Jarzynski sampling : acceleration of rare events and free energy calculation with a bias potential learned from nonequilibrium work”. Bal KM, Journal Of Chemical Theory And Computation 17, 6766 (2021). http://doi.org/10.1021/ACS.JCTC.1C00574
Abstract: We introduce a simple enhanced sampling approach for the calculation of free energy differences and barriers along a one-dimensional reaction coordinate. First, a small number of short nonequilibrium simulations are carried out along the reaction coordinate, and the Jarzynski equality is used to learn an approximate free energy surface from the nonequilibrium work distribution. This free energy estimate is represented in a compact form as an artificial neural network and used as an external bias potential to accelerate rare events in a subsequent molecular dynamics simulation. The final free energy estimate is then obtained by reweighting the equilibrium probability distribution of the reaction coordinate sampled under the influence of the external bias. We apply our reweighted Jarzynski sampling recipe to four processes of varying scales and complexities.spanning chemical reaction in the gas phase, pair association in solution, and droplet nucleation in supersaturated vapor. In all cases, we find reweighted Jarzynski sampling to be a very efficient strategy, resulting in rapid convergence of the free energy to high precision.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 5.245
DOI: 10.1021/ACS.JCTC.1C00574
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“Rheology of amorphous olivine thin films characterized by nanoindentation”. Baral P, Orekhov A, Dohmen R, Coulombier M, Raskin JP, Cordier P, Idrissi H, Pardoen T, Acta Materialia 219, 117257 (2021). http://doi.org/10.1016/J.ACTAMAT.2021.117257
Abstract: The rheological properties of amorphous olivine thin films deposited by pulsed laser deposition have been studied based on ambient temperature nanoindentation under constant strain-rate as well as re-laxation conditions. The amorphous olivine films exhibit a viscoelastic-viscoplastic behavior with a significant rate dependency. The strain-rate sensitivity m is equal to similar to 0 . 05 which is very high for silicates, indicating a complex out-of-equilibrium structure. The minimum apparent activation volume determined from nanoindentation experiments corresponds to Mg and Fe atomic metallic sites in the (Mg,Fe)(2)SiO4 crystalline lattice. The ambient temperature creep behavior of the amorphous olivine films differs very much from the one of single crystal olivine. This behavior directly connects to the recent demonstration of the activation of grain boundary sliding in polycrystalline olivine following grain boundary amorphization under high-stress. (C) 2021 The Authors. Published by Elsevier Ltd on behalf of Acta Materialia Inc.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 5.301
DOI: 10.1016/J.ACTAMAT.2021.117257
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“Rich many-body phase diagram of electrons and holes in doped monolayer transition metal dichalcogenides”. Van der Donck M, Peeters FM, Physical review B 98, 115432 (2018). http://doi.org/10.1103/PHYSREVB.98.115432
Abstract: We use a variational technique to study the many-body phase diagram of electrons and holes in n-doped and p-doped monolayer transition metal dichalcogenides (TMDs). We find a total of four different phases. (i) A fully spin polarized and valley polarized ferromagnetic state. (ii) A state with no global spin polarization but with spin polarization in each valley separately, i.e., spin-valley locking. (iii) A state with spin polarization in one of the valleys and little to no spin polarization in the other valley. (iv) A paramagnetic state with no valley polarization. These phases are separated by first-order phase transitions and are determined by the particle density and the dielectric constant of the substrate. We find that in the presence of a perpendicular magnetic field the four different phases persist. In the case of n-doped MoS2, a fifth phase, which is completely valley polarized but not spin polarized, appears for magnetic fields larger than 7 T and for magnetic fields larger than 23 T completely replaces the second phase.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 8
DOI: 10.1103/PHYSREVB.98.115432
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“Rippling, buckling, and melting of single- and multilayer MoS2”. Singh SK, Neek-Amal M, Costamagna S, Peeters FM, Physical Review B 91, 014101 (2015). http://doi.org/10.1103/PhysRevB.91.014101
Abstract: Large-scale atomistic simulations using the reactive empirical bond order force field approach is implemented to investigate thermal and mechanical properties of single-layer (SL) and multilayer (ML) molybdenum disulfide (MoS2). The amplitude of the intrinsic ripples of SL MoS2 are found to be smaller than those exhibited by graphene (GE). Furthermore, because of the van der Waals interaction between layers, the out-of-plane thermal fluctuations of ML MoS2 decreases rapidly with increasing number of layers. This trend is confirmed by the buckling transition due to uniaxial stress which occurs for a significantly larger applied tension as compared to graphene. For SL MoS2, the melting temperature is estimated to be 3700 K which occurs through dimerization followed by the formation of small molecules consisting of two to five atoms. When different types of vacancies are inserted in the SL MoS2 it results in a decrease of both the melting temperature as well as the stiffness.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 40
DOI: 10.1103/PhysRevB.91.014101
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“Risk assessment and spatial chemical variability of PM collected at selected bus stations”. Godoi RHM, Godoi AFL, de Quadros LC, Polezer G, Silva TOB, Yamamoto CI, Van Grieken R, Potgieter-Vermaak S, Air quality, atmosphere &, health , 1 (2013). http://doi.org/10.1007/S11869-013-0210-2
Abstract: The chemical characterization of particulate matter inside and outside of confined bus shelters has been discerned for the first time. Transit patrons are at risk due to the close vicinity of densely trafficked areas resulting in elevated pollution footprints. Incomplete combustion processes, as well as exhaust and wear and tear emissions from public and personal transportation vehicles, are key contributors to degraded urban air quality and are often implicated as causal to various diseases in humans. Urban planning, therefore, includes efficient public transport systems to mitigate the effect. The bus rapid transit system was inaugurated in Curitiba to ensure dedicated traffic lanes, major bus interchanges and semi-confined bus stops called tube stations. To assess the chemical risk that the passengers are exposed to, an investigation of the aerosol inside and outside five of these tube stations was launched. Electron probe X-ray micro-analysis and X-ray fluorescence were used to determine the elemental composition of individual and of bulk particle samples. An aethalometer quantified the black carbon. Elemental concentrations inside the shelters were in general higher than outside, especially for traffic-related elements. The lead concentration exceeded the NAAS standard at times, although the average was below the guideline. The biogenic, organic and soot clusters showed the highest abundance for the city centre sites. The overall carcinogenic risk could be classed as moderate, and the risk was significant at two sites during one of the sampling campaigns. The non-carcinogenic risk is well below the significant value.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1007/S11869-013-0210-2
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“Risks of atmospheric aerosol for cultural heritage assets in Granada (Spain)”. Cardell C, Urosevic M, Sebastián-Pardo E, Horemans B, Kontozova-Deutsch V, Potgieter-Vermaak S, Bencs L, Anaf KW, De Wael K, Van Grieken R page 45 (2013).
Keywords: H1 Book chapter; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
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“Roadmap on structured waves”. Bliokh KY, Karimi E, Padgett MJ, Alonso MA, Dennis MR, Dudley A, Forbes A, Zahedpour S, Hancock SW, Milchberg HM, Rotter S, Nori F, Ozdemir SK, Bender N, Cao H, Corkum PB, Hernandez-Garcia C, Ren H, Kivshar Y, Silveirinha MG, Engheta N, Rauschenbeutel A, Schneeweiss P, Volz J, Leykam D, Smirnova DA, Rong K, Wang B, Hasman E, Picardi MF, Zayats AV, Rodriguez-Fortuno FJ, Yang C, Ren J, Khanikaev AB, Alu A, Brasselet E, Shats M, Verbeeck J, Schattschneider P, Sarenac D, Cory DG, Pushin DA, Birk M, Gorlach A, Kaminer I, Cardano F, Marrucci L, Krenn M, Marquardt F, Journal of optics 25, 103001 (2023). http://doi.org/10.1088/2040-8986/ACEA92
Abstract: Structured waves are ubiquitous for all areas of wave physics, both classical and quantum, where the wavefields are inhomogeneous and cannot be approximated by a single plane wave. Even the interference of two plane waves, or of a single inhomogeneous (evanescent) wave, provides a number of nontrivial phenomena and additional functionalities as compared to a single plane wave. Complex wavefields with inhomogeneities in the amplitude, phase, and polarization, including topological----- structures and singularities, underpin modern nanooptics and photonics, yet they are equally important, e.g. for quantum matter waves, acoustics, water waves, etc. Structured waves are crucial in optical and electron microscopy, wave propagation and scattering, imaging, communications, quantum optics, topological and non-Hermitian wave systems, quantum condensed-matter systems, optomechanics, plasmonics and metamaterials, optical and acoustic manipulation, and so forth. This Roadmap is written collectively by prominent researchers and aims to survey the role of structured waves in various areas of wave physics. Providing background, current research, and anticipating future developments, it will be of interest to a wide cross-disciplinary audience.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.1
Times cited: 7
DOI: 10.1088/2040-8986/ACEA92
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“Roadside disturbance promotes plant communities with arbuscular mycorrhizal associations in mountain regions worldwide”. Clavel J, Lembrechts J, Lenoir J, Haider S, McDougall K, Nunez MA, Alexander J, Barros A, Milbau A, Seipel T, Pauchard A, Fuentes-Lillo E, Backes AR, Dar P, Reshi ZA, Aleksanyan A, Zong S, Sierra JRA, Aschero V, Verbruggen E, Nijs I, Ecography , e07051 (2024). http://doi.org/10.1111/ECOG.07051
Abstract: We assessed the impact of road disturbances on the dominant mycorrhizal types in ecosystems at the global level and how this mechanism can potentially lead to lasting plant community changes. We used a database of coordinated plant community surveys following mountain roads from 894 plots in 11 mountain regions across the globe in combination with an existing database of mycorrhizal-plant associations in order to approximate the relative abundance of mycorrhizal types in natural and disturbed environments. Our findings show that roadside disturbance promotes the cover of plants associated with arbuscular mycorrhizal (AM) fungi. This effect is especially strong in colder mountain environments and in mountain regions where plant communities are dominated by ectomycorrhizal (EcM) or ericoid-mycorrhizal (ErM) associations. Furthermore, non-native plant species, which we confirmed to be mostly AM plants, are more successful in environments dominated by AM associations. These biogeographical patterns suggest that changes in mycorrhizal types could be a crucial factor in the worldwide impact of anthropogenic disturbances on mountain ecosystems. Indeed, roadsides foster AM-dominated systems, where AM-fungi might aid AM-associated plant species while potentially reducing the biotic resistance against invasive non-native species, often also associated with AM networks. Restoration efforts in mountain ecosystems will have to contend with changes in the fundamental make-up of EcM- and ErM plant communities induced by roadside disturbance.
Keywords: A1 Journal article; Plant and Ecosystems (PLECO) – Ecology in a time of change
Impact Factor: 5.9
DOI: 10.1111/ECOG.07051
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“Role of atomic vacancies and boundary conditions on ballistic thermal transport in graphene nanoribbons”. Scuracchio P, Costamagna, Peeters FM, Dobry A, Physical review : B : condensed matter and materials physics 90, 035429 (2014). http://doi.org/10.1103/PhysRevB.90.035429
Abstract: Quantum thermal transport in armchair and zigzag graphene nanoribbons is investigated in the presence of single atomic vacancies and subject to different boundary conditions. We start with a full comparison of the phonon polarizations and energy dispersions as given by a fifth-nearest-neighbor force-constant model (5NNFCM) and by elasticity theory of continuum membranes (ETCM). For free-edge ribbons, we discuss the behavior of an additional acoustic edge-localized flexural mode, known as fourth acoustic branch (4ZA), which has a small gap when it is obtained by the 5NNFCM. Then, we show that ribbons with supported edges have a sample-size dependent energy gap in the phonon spectrum which is particularly large for in-plane modes. Irrespective to the calculation method and the boundary condition, the dependence of the energy gap for the low-energy optical phonon modes against the ribbon width W is found to be proportional to 1/W for in-plane, and 1/W-2 for out-of-plane phonon modes. Using the 5NNFCM, the ballistic thermal conductance and its contributions from every single phonon mode are then obtained by the nonequilibrium Green's function technique. We found that, while edge and central localized single atomic vacancies do not affect the low-energy transmission function of in-plane phonon modes, they reduce considerably the contributions of the flexural modes. On the other hand, in-plane modes contributions are strongly dependent on the boundary conditions and at low temperatures can be highly reduced in supported-edge samples. These findings could open a route to engineer graphene based devices where it is possible to discriminate the relative contribution of polarized phonons and to tune the thermal transport on the nanoscale.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 20
DOI: 10.1103/PhysRevB.90.035429
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“Role of carbon and nitrogen in Fe2C and Fe2N from first-principles calculations”. Fang CM, van Huis MA, Jansen J, Zandbergen HW, Physical review : B : condensed matter and materials physics 84, 094102 (2011). http://doi.org/10.1103/PhysRevB.84.094102
Abstract: Although Fe2C and Fe2N are technologically important materials, the exact nature of the chemical bonding of C and N atoms and the related impact on the electronic properties are at present unclear. Here, results of first-principles electronic structure calculations for Fe2X (X = C, N) phases are presented. The electronic structure calculations show that the roles of N and C in iron nitrides and carbides are comparable, and that the X-X interactions have significant impact on electronic properties. Accurate analysis of the spatially resolved differences in electron densities reveals a subtle distinction between the chemical bonding and charge transfer of N and C ions.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 24
DOI: 10.1103/PhysRevB.84.094102
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