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“Atomic Collapse in Graphene”. Moldovan D, Peeters FM, Nanomaterials For Security , 3 (2016). http://doi.org/10.1007/978-94-017-7593-9_1
Abstract: When the charge Z of an atom exceeds the critical value of 170, it will undergo a process called atomic collapse which triggers the spontaneous creation of electron-positron pairs. The high charge requirements have prevented the observation of this phenomenon with real atomic nuclei. However, thanks to the relativistic nature of the carriers in graphene, the same physics is accessible at a much lower scale. The atomic collapse analogue in graphene is realized using artificial nuclei which can be created via the deposition of impurities on the surface of graphene or using charged vacancies. These supercritically charged artificial nuclei trap electrons in a sequence of quasi-bound states which can be observed experimentally as resonances in the local density of states.
Keywords: P1 Proceeding; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Times cited: 3
DOI: 10.1007/978-94-017-7593-9_1
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Sobrino Ferná,ndez M (2016) Confinement induced assembly of anisotropic particles : patchy colloids and water molecules. Antwerpen
Keywords: Doctoral thesis; Condensed Matter Theory (CMT)
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Van de Put ML (2016) Modeling of quantum electron transport with applications in energy filtering nanostructures. Antwerpen
Keywords: Doctoral thesis; Condensed Matter Theory (CMT)
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“New insights into the nanostructure of innovative thin film solar cells gained by positron annihilation spectroscopy”. Eijt SWH, Shi W, Mannheim A, Butterling M, Schut H, Egger W, Dickmann M, Hugenschmidt C, Shakeri B, Meulenberg RW, Callewaert V, Saniz R, Partoens B, Barbiellini B, Bansil A, Melskens J, Zeman M, Smets AHM, Kulbak M, Hodes G, Cahen D, Brück E, Journal of physics : conference series 791, 012021 (2017). http://doi.org/10.1088/1742-6596/791/1/012021
Abstract: Recent studies showed that positron annihilation methods can provide key insights into the nanostructure and electronic structure of thin film solar cells. In this study, positron annihilation lifetime spectroscopy (PALS) is applied to investigate CdSe quantum dot (QD) light absorbing layers, providing evidence of positron trapping at the surfaces of the QDs. This enables one to monitor their surface composition and electronic structure. Further, 2D-Angular Correlation of Annihilation Radiation (2D-ACAR) is used to investigate the nanostructure of divacancies in photovoltaic-high-quality a-Si:H films. The collected momentum distributions were converted by Fourier transformation to the direct space representation of the electron-positron autocorrelation function. The evolution of the size of the divacancies as a function of hydrogen dilution during deposition of a-Si:H thin films was examined. Finally, we present a first positron Doppler Broadening of Annihilation Radiation (DBAR) study of the emerging class of highly efficient thin film solar cells based on perovskites.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Times cited: 1
DOI: 10.1088/1742-6596/791/1/012021
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“Silver Ions Direct Twin-Plane Formation during the Overgrowth of Single-Crystal Gold Nanoparticles”. Grzelczak M, Sanchez-Iglesias A, Heidari H, Bals S, Pastoriza-Santos I, Perez-Juste J, Liz-Marzan LM, ACS Omega 1, 177 (2016). http://doi.org/10.1021/ACSOMEGA.6B00066
Abstract: It is commonly agreed that the crystalline structure of seeds dictates the crystallinity of final nanoparticles in a seeded-growth process. Although the formation of monocrystalline particles does require the use of single-crystal seeds, twin planes may stem from either single-or polycrystalline seeds. However, experimental control over twin-plane formation remains difficult to achieve synthetically. Here, we show that a careful interplay between kinetics and selective surface passivation offers a unique handle over the emergence of twin planes (in decahedra and triangles) during the growth over single-crystalline gold nanoparticles of quasi-spherical shape. Twinning can be suppressed under conditions of slow kinetics in the presence of silver ions, yielding single-crystalline particles with high-index facets.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 18
DOI: 10.1021/ACSOMEGA.6B00066
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“Many-body electron correlations in graphene”. Neilson D, Perali A, Zarenia M, (mbt18) 702, 012008 (2016). http://doi.org/10.1088/1742-6596/702/1/012008
Abstract: The conduction electrons in graphene promise new opportunities to access the region of strong many-body electron-electron correlations. Extremely high quality, atomically flat two-dimensional electron sheets and quasi-one-dimensional electron nanoribbons with tuneable band gaps that can be switched on by gates, should exhibit new many-body phenomena that have long been predicted for the regions of phase space where the average Coulomb repulsions between electrons dominate over their Fermi energies. In electron nanoribbons a few nanometres wide etched in monolayers of graphene, the quantum size effects and the van Hove singularities in their density of states further act to enhance electron correlations. For graphene multilayers or nanoribbons in a double unit electron-hole geometry, it is possible for the many-body electron-hole correlations to be made strong enough to stabilise high-temperature electron- hole superfluidity.
Keywords: P1 Proceeding; Condensed Matter Theory (CMT)
Times cited: 3
DOI: 10.1088/1742-6596/702/1/012008
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“Plasma based co2 conversion: a combined modeling and experimental study”. Bogaerts A, Snoeckx R, Berthelot A, Heijkers S, Wang W, Sun S, Van Laer K, Ramakers M, Michielsen I, Uytdenhouwen Y, Meynen V, Cool P, Hakone Xv: International Symposium On High Pressure Low Temperature Plasma Chemistry: With Joint Cost Td1208 Workshop: Non-equilibrium Plasmas With Liquids For Water And Surface Treatment (2016)
Abstract: In recent years there is increased interest in plasma-based CO2 conversion. Several plasma setups are being investigated for this purpose, but the most commonly used ones are a dielectric barrier discharge (DBD), a microwave (MW) plasma and a gliding arc (GA) reactor. In this proceedings paper, we will show results from our experiments in a (packed bed) DBD reactor and in a vortex-flow GA reactor, as well as from our model calculations for the detailed plasma chemistry in a DBD, MW and GA, for pure CO2 as well as mixtures of CO2 with N-2, CH4 and H2O.
Keywords: P1 Proceeding; Laboratory of adsorption and catalysis (LADCA); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
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“Theoretical study of silicene and germanene”. Houssa M, van den Broek B, Scalise E, Pourtois G, Afanas'ev VV, Stesmans A, Graphene, Ge/iii-v, And Emerging Materials For Post Cmos Applications 5 (2013). http://doi.org/10.1149/05301.0051ECST
Abstract: The structural and electronic properties of silicene and germanene on metallic and non-metallic substrates are investigated theoretically, using first-principles simulations. We first study the interaction of silicene with Ag(111) surfaces, focusing on the (4x4) silicene/Ag structure. Due to symmetry breaking in the silicene layer (nonequivalent number of top and bottom Si atoms), silicene is predicted to be semiconducting, with a computed energy gap of about 0.3 eV. However, the charge transfer occurring at the silicene/Ag(111) interface leads to an overall metallic system. We next investigate the interaction of silicene and germanene with hexagonal non-metallic substrates, namely ZnS and ZnSe. On reconstructed (semiconducting) (0001) ZnS or ZnSe surfaces, silicene and germanene are found to be semiconducting. Remarkably, the nature (indirect or direct) and magnitude of their energy band gap can be controlled by an out-of-plane electric field.
Keywords: P1 Proceeding; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Times cited: 6
DOI: 10.1149/05301.0051ECST
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“Atomically resolved EELS mapping of the interfacial structure of epitaxially strained LaNiO3/LaAlO3 superlattices”. N Gauquelin E Benckiser M K Kinyanjui M Wu Y Lu G Christiani G Logvenov H-U Habermeier U Kaiser B Keimer and G A Botton, Physical Review B 90, 195140 (2014). http://doi.org/10.1103/PhysRevB.90.195140
Abstract: The interfacial atomic structure of a metallic LaNiO3/LaAlO3 superlattice grown on a LaSrAlO4 substrate was
investigated using a combination of atomically resolved electron energy loss spectroscopy (EELS) at the Al K,
Al L2,3, Sr L2,3, Ni L2,3, La M4,5, and O K edges as well as hybridization mapping of selected features of the O
K-edge fine structure.We observe an additional La1−xSrxAl1−yNiyO3 layer at the substrate-superlattice interface,
possibly linked to diffusion of Al and Sr into the growing film or a surface reconstruction due to Sr segregation.
The roughness of the LaNiO3/LaAlO3 interfaces is found to be on average around one pseudocubic unit cell. The
O K-edge EELS spectra revealed reduced spectral weight of the prepeak derived from Ni-O hybridized states in
the LaNiO3 layers. We rule out oxygen nonstoichiometry of the LaNiO3 layers and discuss changes in the Ni-O
hybridization due to heterostructuring as possible origin.
Keywords: A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Times cited: 17
DOI: 10.1103/PhysRevB.90.195140
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“Local lattice distortion and anisotropic modulation in Epitaxially Strained LaNiO3/LaAlO3 hetero-structures”. M K Kinyanjui N Gauquelin E Benckiser H –U Habermeier B Keimer U Kaiser and GA Botton, Applied Physics Letters 104, 221909 (2014). http://doi.org/10.1063/1.4881557
Abstract: Using a complementary combination of x-ray diffraction and atomically resolved imaging we investigated the lattice structure of epitaxial LaNiO3/LaAlO3 superlattices grown on a compressive-strain inducing LaSrAlO4 (001) substrate. A refinement of the structure obtained from the x-ray data revealed the monoclinic I 2/c 1 1 space group. The (Ni/Al)O6 octahedral rotation angle perpendicular to the superlattice plane is enhanced, and the one parallel to the plane is reduced with respect to the corresponding bulk values. High-angle annular dark field imaging was used to determine the lattice parameters within the superlattice unit cell. High-resolution electron microscopy images of the oxygen atoms are consistent with the x-ray results.
Keywords: A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Times cited: 22
DOI: 10.1063/1.4881557
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“Composition-dependent charge transfer and phase separation in the V1-xRexO2 solid solution”. Mikhailova D, Kuratieva NN, Utsumi Y, Tsirlin AA, Abakumov AM, Schmidt M, Oswald S, Fuess H, Ehrenberg H, Journal of the Chemical Society : Dalton transactions 46, 1606 (2017). http://doi.org/10.1039/C6DT04389E
Abstract: The substitution of vanadium in vanadium dioxide VO2 influences the critical temperatures of structural and metal-to-insulator transitions in different ways depending on the valence of the dopant. Rhenium adopts valence states between + 4 and + 7 in an octahedral oxygen surrounding and is particularly interesting in this context. Structural investigation of V1-xRexO2 solid solutions (0.01 <= x <= 0.30) between 80 and 1200 K using synchrotron X-ray powder diffraction revealed only two polymorphs that resemble VO2: the low-temperature monoclinic MoO2-type form (space group P2(1)/c), and the tetragonal rutile-like form (space group P4(2)/mnm). However, for compositions with 0.03 < x <= 0.15 a phase separation in the solid solution was observed below 1000 K upon cooling down from 1200 K, giving rise to two isostructural phases with slightly different lattice parameters. This is reflected in the appearance of two metal-toinsulator transition temperatures detected by magnetization and specific heat measurements. Comprehensive X-ray photoelectron spectroscopy studies showed that an increased amount of Re leads to a change in the Re valence state from solely Re6+ at a low doping level (<= 3 at% Re) via mixed-valence states Re4+/Re6+ for at least 0.03 < x <= 0.10, up to nearly pure Re4+ in V0.70Re0.30O2. Thus, compositions V1-xRexO2 with only one valence state of Re in the material (Re6+ or Re4+) can be obtained as a single phase, while intermediate compositions are subjected to a phase separation, presumably due to different valence states of Re.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4.029
Times cited: 1
DOI: 10.1039/C6DT04389E
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“Inkjet printing multideposited YBCO on CGO/LMO/MgO/Y2O3/Al2O3/Hastelloy tape for 2G-coated conductors”. Roxana Vlad V, Bartolome E, Vilardell M, Calleja A, Meledin A, Obradors X, Puig T, Ricart S, Van Tendeloo G, Usoskin A, Lee S, Petrykin V, Molodyk A, IEEE transactions on applied superconductivity 28, 6601805 (2018). http://doi.org/10.1109/TASC.2018.2808403
Abstract: We present the preparation of a new architecture of coated conductor by Inkjet printing of low fluorine YBa2Cu3O7-x (YBCO) on top of SuperOx tape: CGO/LMO/IBAD-MgO/Y2O3/Al-2 O-3/Hastelloy. A five-layered multideposited, 475-nm-thick YBCO film was structurally and magnetically characterized. A good texture was achieved using this combination of buffer layers, requiring only a 30-nm-thin ion-beam-assisted deposition (IBAD)-MgO layer. The LF-YBCO CC reaches self-field critical current density values of J(c)(GB) similar to NJ 15.9 MA/cm(2) (5 K), similar to 1.23 MA/cm(2) (77 K) corresponding to an I-c (77 K) = 58.4 A/cm-width. Inkjet printing offers a flexible and cost effective method for YBCO deposition, allowing patterning of structures.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.288
Times cited: 2
DOI: 10.1109/TASC.2018.2808403
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“Thick secondary phase pinning-enhanced YBCO films on technical templates”. Sieger M, Pahlke P, Lao M, Meledin A, Eisterer M, Van Tendeloo G, Schultz L, Nielsch K, Huehne R, IEEE transactions on applied superconductivity 28, 8000505 (2018). http://doi.org/10.1109/TASC.2018.2799419
Abstract: The critical current I-c(B) of YBa2Cu3O7-delta (YBCO) coated conductors can be increased by growing thicker superconductor layers as well as improving the critical current density J(c)(B) by the incorporation of artificial pinning centers. We studied the properties of pulsed laser deposited BaHfO3 (BHO)-doped YBCO films with thicknesses of up to 5 mu m on buffered rolling-assisted biaxially textured Ni-5 at % W tape and alternating beam assisted deposition textured Yttrium-stabilized ZrO2 layers on stainless steel. X-Ray diffraction confirms the epitaxial growth of the superconductor on the buffered metallic template. BHO additions reduce the film porosity and lower the probability to grow misoriented grains, hence preventing the J(c) decrease observed in undoped YBCO films with thicknesses > 2 mu m. Thereby, a continuous increase in I-c at 77 K is achieved. A mixed structure of secondary phase nanorods and platelets with different orientations increases J(c)(B) in the full angular range and simultaneously lowers the J(c) anisotropy compared to pristine YBCO.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.288
Times cited: 1
DOI: 10.1109/TASC.2018.2799419
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“Possible Mechanism of Glucose Uptake Enhanced by Cold Atmospheric Plasma: Atomic Scale Simulations”. Razzokov J, Yusupov M, Bogaerts A, Plasma 1 (2018). http://doi.org/10.3390/plasma1010011
Abstract: Cold atmospheric plasma (CAP) has shown its potential in biomedical applications, such as wound healing, cancer treatment and bacterial disinfection. Recent experiments have provided evidence that CAP can also enhance the intracellular uptake of glucose molecules which is important in diabetes therapy. In this respect, it is essential to understand the underlying mechanisms of intracellular glucose uptake induced by CAP, which is still unclear. Hence, in this study we try to elucidate the possible mechanism of glucose uptake by cells by performing computer simulations. Specifically, we study the transport of glucose molecules through native and oxidized membranes. Our simulation results show that the free energy barrier for the permeation of glucose molecules across the membrane decreases upon increasing the degree of oxidized lipids in the membrane. This indicates that the glucose permeation rate into cells increases when the CAP oxidation level in the cell membrane is increased.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
DOI: 10.3390/plasma1010011
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“Firsto order phase transformation in the Ni-Al system”. Tanner LE, Shapiro SM, Krumhansl JA, Schryvers D, Noda Y, Yamada Y, Barsch GR, Gooding R, Moss SC, Metallurgy and Ceramics (1992)
Abstract: First-order displacive phase transformations in alloys and compounds are of high technological importance. We have studied this class of phase transformation in the high-temperature-stable Ni-Al f32(B2) phase as a function of composition, temperature, and stress using transmission electron microscopy and neutron scattering. The results show in detail the direct relationship between the unusually low energies of the transformation-related phonon modes and the development of pre-transformation microstructures (strain-embryos, etc.) via anharmonic coupling processes that ultimately lead to the nucleation and growth of the low-temperature martensitic phases. With these results, it is now possible to develop effective models for nonclassical heterogeneous nucleation of martensite transformations in bulk materials. This tills a critical gap and sets the stage for us to proceed in developing a more global understanding of condensed matter transformations including the coupling of displacive with replacive mechanisms.
Keywords: A3 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
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“Two-dimensional electron systems in perovskite oxide heterostructures : role of the polarity-induced substitutional defects”. Lin S-C, Kuo C-T, Shao Y-C, Chuang Y-D, Geessinck J, Huijben M, Rueff J-P, Graff IL, Conti G, Peng Y, Bostwick A, Gullikson E, Nemsak S, Vailionis A, Gauquelin N, Verbeeck J, Ghiringhelli G, Schneider CM, Fadley CS, Physical review materials 4, 115002 (2020). http://doi.org/10.1103/PHYSREVMATERIALS.4.115002
Abstract: The discovery of a two-dimensional electron system (2DES) at the interfaces of perovskite oxides such as LaAlO3 and SrTiO3 has motivated enormous efforts in engineering interfacial functionalities with this type of oxide heterostructures. However, the fundamental origins of the 2DES are still not understood, e.g., the microscopic mechanisms of coexisting interface conductivity and magnetism. Here we report a comprehensive spectroscopic investigation on the depth profile of 2DES-relevant Ti 3d interface carriers using depthand element-specific techniques like standing-wave excited photoemission and resonant inelastic scattering. We found that one type of Ti 3d interface carriers, which give rise to the 2DES are located within three unit cells from the n-type interface in the SrTiO3 layer. Unexpectedly, another type of interface carriers, which are polarity-induced Ti-on-Al antisite defects, reside in the first three unit cells of the opposing LaAlO3 layer (similar to 10 angstrom). Our findings provide a microscopic picture of how the localized and mobile Ti 3d interface carriers distribute across the interface and suggest that the 2DES and 2D magnetism at the LaAlO3/SrTiO3 interface have disparate explanations as originating from different types of interface carriers.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.4
Times cited: 7
DOI: 10.1103/PHYSREVMATERIALS.4.115002
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“Seeded growth combined with cation exchange for the synthesis of anisotropic Cu2-xS/ZnS, Cu2-xS, and CuInS2 nanorods”. Xia C, Pedrazo-Tardajos A, Wang D, Meeldijk JD, Gerritsen HC, Bals S, de Donega CM, Chemistry of materials 33, 102 (2021). http://doi.org/10.1021/ACS.CHEMMATER.0C02817
Abstract: Colloidal copper(I) sulfide (Cu2-xS) nanocrystals (NCs) have attracted much attention for a wide range of applications because of their unique optoelectronic properties, driving scientists to explore the potential of using Cu2-xS NCs as seeds in the synthesis of heteronanocrystals to achieve new multifunctional materials. Herein, we developed a multistep synthesis strategy toward Cu2-xS/ZnS heteronanorods. The Janus-type Cu2-xS/ZnS heteronanorods are obtained by the injection of hexagonal high-chalcocite Cu2-xS seed NCs in a hot zinc oleate solution in the presence of suitable surfactants, 20 s after the injection of sulfur precursors. The Cu2-xS seed NCs undergo rapid aggregation and coalescence in the first few seconds after the injection, forming larger NCs that act as the effective seeds for heteronucleation and growth of ZnS. The ZnS heteronucleation occurs on a single (100) facet of the Cu2-xS seed NCs and is followed by fast anisotropic growth along a direction that is perpendicular to the c-axis, thus leading to Cu2-xS/ZnS Janus-type heteronanorods with a sharp heterointerface. Interestingly, the high-chalcocite crystal structure of the injected Cu2-xS seed NCs is preserved in the Cu2-xS segments of the heteronanorods because of the highthermodynamic stability of this Cu2-xS phase. The Cu2-xS/ZnS heteronanorods are subsequently converted into single-component Cu2-xS and CuInS2 nanorods by postsynthetic topotactic cation exchange. This work expands the possibilities for the rational synthesis of colloidal multicomponent heteronanorods by allowing the design principles of postsynthetic heteroepitaxial seeded growth and nanoscale cation exchange to be combined, yielding access to a plethora of multicomponent heteronanorods with diameters in the quantum confinement regime.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 10
DOI: 10.1021/ACS.CHEMMATER.0C02817
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“Grain boundaries as a diffusion-limiting factor in lithium-rich NMC cathodes for high-energy lithium-ion batteries”. Abakumov AM, Li C, Boev A, Aksyonov DA, Savina AA, Abakumova TA, Van Tendeloo G, Bals S, ACS applied energy materials 4, 6777 (2021). http://doi.org/10.1021/ACSAEM.1C00872
Abstract: High-energy lithium-rich layered transition metal oxides are capable of delivering record electrochemical capacity and energy density as positive electrodes for Li-ion batteries. Their electrochemical behavior is extremely complex due to sophisticated interplay between crystal structure, electronic structure, and defect structure. Here we unravel an extra level of this complexity by revealing that the most typical representative Li1.2Ni0.13Mn0.54Co0.13O2 material, prepared by a conventional coprecipitation technique with Na2CO3 as a precipitating agent, contains abundant coherent (001) grain boundaries with a Na-enriched P2-structured block due to segregation of the residual sodium traces. The trigonal prismatic oxygen coordination of Na triggers multiple nanoscale twinning, giving rise to incoherent (104) boundaries. The cationic layers at the (001) grain boundaries are filled with transition metal cations being Mn-depleted and Co-enriched; this makes them virtually not permeable for the Li+ cations, and therefore they negatively influence the Li diffusion in and out of the spherical agglomerates. These results demonstrate that besides the mechanisms intrinsic to the crystal and electronic structure of Li-rich cathodes, their rate capability might also be depreciated by peculiar microstructural aspects. Dedicated engineering of grain boundaries opens a way for improving inherently sluggish kinetics of these materials.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Times cited: 4
DOI: 10.1021/ACSAEM.1C00872
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“Boosting aerobic microbial protein productivity and quality on brewery wastewater : impact of anaerobic acidification, high-rate process and biomass age”. Papini G, Muys M, Van Winckel T, Meerburg FA, Van Beeck W, Vermeir P, Vlaeminck SE, Bioresource technology 368, 128285 (2023). http://doi.org/10.1016/J.BIORTECH.2022.128285
Abstract: Consortia of aerobic heterotrophic bacteria (AHB) are appealing as sustainable alternative protein ingredient for aquaculture given their high nutritional qualities, and their production potential on feed-grade industrial wastewater. Today, the impacts of pre-treatment, bioprocess choice and key parameter settings on AHB productivity and nutritional properties are unknown. This study investigated for the first time AHB microbial protein production effects based on (i) raw vs anaerobically fermented brewery wastewater, (ii) high-rate activated sludge (HRAS) without vs with feast-famine conditions, and (iii) three short solid retention time (SRT): 0.25, 0.50 and 1.00 d. High biomass (4.4–8.0 g TSS/L/d) and protein productivities (1.9–3.2 g protein/L/d) were obtained while achieving COD removal efficiencies up to 98 % at SRT 0.50 d. The AHB essential amino acid (EAA) profiles were above rainbow trout requirements, excluding the S-containing EAA, highlighting the AHB biomass replacement potential for unsustainable fishmeal in salmonid diets.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 11.4
DOI: 10.1016/J.BIORTECH.2022.128285
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“Plasma-catalytic ammonia synthesis in a dielectric barrier discharge reactor: A combined experimental study and kinetic modeling”. Andersen Ja, Holm Mc, van 't Veer K, Christensen Jm, Østberg M, Bogaerts A, Jensen Ad, Chemical engineering journal 457, 141294 (2023). http://doi.org/10.1016/j.cej.2023.141294
Abstract: Plasma-catalytic ammonia synthesis in a dielectric barrier discharge reactor has emerged as a possible route for electrification of nitrogen fixation. In this study, we use a combination of experiments and a plasma kinetic model to investigate the ammonia synthesis from N2 and H2, both with and without a solid packing material in the plasma zone. The effect of plasma power, feed flow rate, N2:H2 feed ratio, gas residence time, temperature, and packing material (MgAl2O4 alone or impregnated with Co or Ru) on the ammonia synthesis rate were examined in the experiments. The kinetic model was employed to improve our understanding of the ammonia formation pathways and identify possible changes in these pathways when altering the N2:H2 feed ratio. A higher NH3 synthesis rate was achieved when increasing the feed flow rate, as well as when increasing the gas tem-perature from 100 to 200 ◦C when a packing material was present in the plasma. At the elevated temperature of 200 ◦C, an optimum in the NH3 synthesis rate was observed at an equimolar feed ratio (N2:H2 =1:1) for the plasma alone and MgAl2O4, while a N2-rich feed was favored for Ru/MgAl2O4 and Co/MgAl2O4. The optimum in the synthesis rate with the N2-rich feed, where high energy electrons are more likely to collide with N2, suggests that the rate-limiting step is the dissociation of N2 in the gas phase. This is supported by the kinetic model when packing material was used. However, for the plasma alone, the model found that the N2 dissociation is only rate limiting in H2-rich feeds, whereas the limited access to H in N2-rich feeds makes the hydrogenation of N species limiting.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 15.1
DOI: 10.1016/j.cej.2023.141294
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“Post-plasma quenching to improve conversion and energy efficiency in a CO2 microwave plasma”. Mercer Er, Van Alphen S, van Deursen Cfam, Righart Twh, Bongers Wa, Snyders R, Bogaerts A, van de Sanden Mcm, Peeters Fjj, Fuel 334, 126734 (2023). http://doi.org/10.1016/j.fuel.2022.126734
Abstract: Transforming CO2 into value-added chemicals is crucial to realizing a carbon–neutral economy, and plasma-based conversion, a Power-2-X technology, offers a promising route to realizing an efficient and scalable process. This paper investigates the effects of post-plasma placement of a converging–diverging nozzle in a vortex-stabilized 2.45 GHz CO2 microwave plasma reactor to increase energy efficiency and conversion. The CDN leads to a 21 % relative increase in energy efficiency (31 %) and CO2 conversion (13 %) at high flow rates and near-atmospheric conditions. The most significant performance improvement was seen at low flow rates and sub-atmospheric pressure (300 mbar), where energy efficiency was 23 % and conversion was 28 %, a 71 % relative increase over conditions without the CDN. Using CFD simulations, we found that the CDN produces a change in the flow geometry, leading to a confined temperature profile at the height of the plasma, and forced extraction of CO to the post-CDN region.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 7.4
DOI: 10.1016/j.fuel.2022.126734
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“Ammonia decomposition in a dielectric barrier discharge plasma: Insights from experiments and kinetic modeling”. Andersen Ja, van 't Veer K, Christensen Jm, Østberg M, Bogaerts A, Jensen Ad, Chemical engineering science 271, 118550 (2023). http://doi.org/10.1016/j.ces.2023.118550
Abstract: Utilizing ammonia as a storage medium for hydrogen is currently receiving increased attention. A possible method to retrieve the hydrogen is by plasma-catalytic decomposition. In this work, we combined an experimental study, using a dielectric barrier discharge plasma reactor, with a plasma kinetic model, to get insights into the decomposition mechanism. The experimental results revealed a similar effect on the ammonia conversion when changing the flow rate and power, where increasing the specific energy input (higher power or lower flow rate) gave an increased conversion. A conversion as high as 82 % was achieved at a specific energy input of 18 kJ/Nl. Furthermore, when changing the discharge volume from 31 to 10 cm3, a change in the plasma distribution factor from 0.2 to 0.1 was needed in the model to best describe the conversions of the experiments. This means that a smaller plasma volume caused a higher transfer of energy through micro-discharges (non-uniform plasma), which was found to promote the decomposition of ammonia. These results indicate that it is the collisions between NH3 and the high-energy electrons that initiate the decomposition. Moreover, the rate of ammonia destruction was found by the model to be in the order of 1022 molecules/(cm3 s) during the micro-discharges, which is 5 to 6 orders of magnitude higher than in the afterglows. A considerable re-formation of ammonia was found to take place in the afterglows, limiting the overall conversion. In addition, the model revealed that implementation of packing material in the plasma introduced high concentrations of surface-bound hydrogen atoms, which introduced an additional ammonia re-formation pathway through an Eley-Rideal reaction with gas phase NH2. Furthermore, a more uniform plasma is predicted in the presence of MgAl2O4, which leads to a lower average electron energy during micro-discharges and a lower conversion (37 %) at a comparable residence time for the plasma alone (51 %).
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.7
DOI: 10.1016/j.ces.2023.118550
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“Acquired non-thermal plasma resistance mediates a shift towards aerobic glycolysis and ferroptotic cell death in melanoma”. Lin A, Sahun M, Biscop E, Verswyvel H, De Waele J, De Backer J, Theys C, Cuypers B, Laukens K, Berghe WV, Smits E, Bogaerts A, Drug resistance updates 67, 100914 (2023). http://doi.org/10.1016/j.drup.2022.100914
Abstract: To gain insights into the underlying mechanisms of NTP therapy sensitivity and resistance, using the firstever
NTP-resistant cell line derived from sensitive melanoma cells (A375).
Methods: Melanoma cells were exposed to NTP and re-cultured for 12 consecutive weeks before evaluation
against the parental control cells. Whole transcriptome sequencing analysis was performed to identify differentially
expressed genes and enriched molecular pathways. Glucose uptake, extracellular lactate, media acidification,
and mitochondrial respiration was analyzed to determine metabolic changes. Cell death inhibitors were
used to assess the NTP-induced cell death mechanisms, and apoptosis and ferroptosis was further validated via
Annexin V, Caspase 3/7, and lipid peroxidation analysis.
Results: Cells continuously exposed to NTP became 10 times more resistant to NTP compared to the parental cell
line of the same passage, based on their half-maximal inhibitory concentration (IC50). Sequencing and metabolic
analysis indicated that NTP-resistant cells had a preference towards aerobic glycolysis, while cell death analysis
revealed that NTP-resistant cells exhibited less apoptosis but were more vulnerable to lipid peroxidation and
ferroptosis.
Conclusions: A preference towards aerobic glycolysis and ferroptotic cell death are key physiological changes in
NTP-resistance cells, which opens new avenues for further, in-depth research into other cancer types.
Keywords: A1 Journal article; Pharmacology. Therapy; ADReM Data Lab (ADReM); Center for Oncological Research (CORE); Proteinscience, proteomics and epigenetic signaling (PPES); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 24.3
DOI: 10.1016/j.drup.2022.100914
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“Postplasma Catalytic Model for NO Production: Revealing the Underlying Mechanisms to Improve the Process Efficiency”. Eshtehardi HA, van 't Veer K, Delplancke M-P, Reniers F, Bogaerts A, ACS Sustainable Chemistry and Engineering 11, 1720 (2023). http://doi.org/10.1021/acssuschemeng.2c05665
Abstract: Plasma catalysis is emerging for plasma-assisted gas conversion processes. However, the underlying mechanisms of plasma catalysis are poorly understood. In this work, we present a 1D heterogeneous catalysis model with axial dispersion (i.e., accounting for back-mixing and molecular diffusion of fluid elements in the process stream in the axial direction), for plasma-catalytic NO production from N2/O2 mixtures. We investigate the concentration and reaction rates of each species formed as a function of time and position across the catalyst, in order to determine the underlying mechanisms. To obtain insights into how the performance of the process can be further improved, we also study how changes in the postplasma gas flow composition entering the catalyst bed and in the operation conditions of the catalytic stage affect the performance of NO production.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 8.4
DOI: 10.1021/acssuschemeng.2c05665
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“Bioactive Nonthermal Biocompatible Plasma Enhances Migration on Human Gingival Fibroblasts”. Han I, Song IS, Choi SA, Lee T, Yusupov M, Shaw P, Bogaerts A, Choi EH, Ryu JJ, Advanced healthcare materials 12, 2200527 (2023). http://doi.org/10.1002/adhm.202200527
Abstract: This study hypothesizes that the application of low-dose nonthermal biocompatible dielectric barrier discharge plasma (DBD-NBP) to human gingival fibroblasts (HGFs) will inhibit colony formation but not cell death and induce matrix metalloproteinase (MMP) expression, extracellular matrix (ECM) degradation, and subsequent cell migration, which can result in enhanced wound healing. HGFs treated with plasma for 3 min migrate to each other across the gap faster than those in the control and 5-min treatment groups on days 1 and 3. The plasma-treated HGFs show significantly high expression levels of the cell cycle arrest-related p21 gene and enhanced MMP activity. Focal adhesion kinase (FAK) mediated attenuation of wound healing or actin cytoskeleton rearrangement, and plasma-mediated reversal of this attenuation support the migratory effect of DBD-NBP. Further, this work performs computer simulations to investigate the effect of oxidation on the stability and conformation of the catalytic kinase domain (KD) of FAK. It is found that the oxidation of highly reactive amino acids (AAs) Cys427, Met442, Cys559, Met571, Met617, and Met643 changes the conformation and increases the structural flexibility of the FAK protein and thus modulates its function and activity. Low-dose DBD-NBP-induces host cell cycle arrest, ECM breakdown, and subsequent migration, thus contributing to the enhanced wound healing process.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 10
DOI: 10.1002/adhm.202200527
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“Methane coupling in nanosecond pulsed plasmas: Correlation between temperature and pressure and effects on product selectivity”. Morais E, Delikonstantis E, Scapinello M, Smith G, Stefanidis GD, Bogaerts A, Chemical engineering journal 462, 142227 (2023). http://doi.org/10.1016/j.cej.2023.142227
Abstract: We present a zero-dimensional kinetic model to characterise specifically the gas-phase dynamics of methane
conversion in a nanosecond pulsed discharge (NPD) plasma reactor. The model includes a systematic approach to
capture the nanoscale power discharges and the rapid ensuing changes in electric field, gas and electron temperature,
as well as species densities. The effects of gas temperature and reactor pressure on gas conversion and
product selectivity are extensively investigated and validated against experimental work. We discuss the
important reaction pathways and provide an analysis of the dynamics of the heating and cooling mechanisms. H
radicals are found to be the most populous plasma species and they participate in hydrogenation and dehydrogenation
reactions, which are the dominant recombination reactions leading to C2H4 and C2H2 as main
products (depending on the pressure).
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 15.1
DOI: 10.1016/j.cej.2023.142227
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“Templated Out‐of‐Equilibrium Self‐Assembly of Branched Au Nanoshells”. Marchetti A, Gori A, Ferretti AM, Esteban DA, Bals S, Pigliacelli C, Metrangolo P, Small , 2206712 (2023). http://doi.org/10.1002/smll.202206712
Abstract: Out-of-equilibrium self-assembly of metal nanoparticles (NPs) has been devised using different types of strategies and fuels, but the achievement of finite 3D structures with a controlled morphology through this assembly mode is still rare. Here we used a spherical peptide-gold superstructure (PAuSS) as a template to control the out-of-equilibrium self-assembly of Au NPs, obtaining a transient 3D branched Au-nanoshell (BAuNS) stabilized by sodium dodecyl sulphate (SDS). The BAuNS dismantled upon concentration gradient equilibration over time in the solution, leading to NPs disassembly. Notably, BAuNS assembly and disassembly favoured temporary interparticle plasmonic coupling, leading to a remarkable oscillation of their optical properties.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 13.3
Times cited: 1
DOI: 10.1002/smll.202206712
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“Decoupling the Characteristics of Magnetic Nanoparticles for Ultrahigh Sensitivity”. Chowdhury MS, Rösch EL, Esteban DA, Janssen K-J, Wolgast F, Ludwig F, Schilling M, Bals S, Viereck T, Lak A, Nano letters 23, 58 (2023). http://doi.org/10.1021/acs.nanolett.2c03568
Abstract: Immunoassays exploiting magnetization dynamics of magnetic nanoparticles are highly promising for mix-and-measure, quantitative, and point-of-care diagnostics. However, how single-core magnetic nanoparticles can be employed to reduce particle concentration and concomitantly maximize assay sensitivity is not fully understood. Here, we design monodisperse Néel and Brownian relaxing magnetic nanocubes (MNCs) of different sizes and compositions. We provide insights into how to decouple physical properties of these MNCs to achieve ultrahigh sensitivity. We find that tri-component-based Zn0.06 Co0.80Fe2.14 O4 particles, with out-of-phase to initial magnetic susceptibility χ /χ ratio of 0.47 out of 0.50 for magnetically blocked ideal particles, show the ultrahigh magnetic sensitivity by providing rich magnetic particle spectroscopy (MPS) harmonics spectrum despite bearing lower saturation magnetization than di-component Zn0.1Fe2.9O4 having high saturation magnetization. The Zn0.06Co0.80Fe2.14O4 MNCs, coated with catechol-based polyethylene glycol ligands, measured by our benchtop MPS show three orders of magnitude better particle LOD than that of commercial nanoparticles of comparable size.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 10.8
Times cited: 1
DOI: 10.1021/acs.nanolett.2c03568
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“NH3and HNOxFormation and Loss in Nitrogen Fixation from Air with Water Vapor by Nonequilibrium Plasma”. Vervloessem E, Gromov M, De Geyter N, Bogaerts A, Gorbanev Y, Nikiforov A, ACS Sustainable Chemistry and Engineering 11, 4289 (2023). http://doi.org/10.1021/acssuschemeng.3c00208
Abstract: The current global energy crisis indicated that increasing our
insight into nonfossil fuel nitrogen fixation pathways for synthetic fertilizer
production is more crucial than ever. Nonequilibrium plasma is a good candidate
because it can use N2 or air as a N source and water directly as a H source, instead
of H2 or fossil fuel (CH4). In this work, we investigate NH3 gas phase formation
pathways from humid N2 and especially humid air up to 2.4 mol % H2O (100%
relative humidity at 20 °C) by optical emission spectroscopy and Fouriertransform
infrared spectroscopy. We demonstrate that the nitrogen fixation
capacity is increased when water vapor is added, as this enables HNO2 and NH3
production in both N2 and air. However, we identified a significant loss
mechanism for NH3 and HNO2 that occurs in systems where these species are
synthesized simultaneously; i.e., downstream from the plasma, HNO2 reacts with NH3 to form NH4NO2, which rapidly decomposes
into N2 and H2O. We also discuss approaches to prevent this loss mechanism, as it reduces the effective nitrogen fixation when not
properly addressed and therefore should be considered in future works aimed at optimizing plasma-based N2 fixation. In-line removal
of HNO2 or direct solvation in liquid are two proposed strategies to suppress this loss mechanism. Indeed, using liquid H2O is
beneficial for accumulation of the N2 fixation products. Finally, in humid air, we also produce NH4NO3, from the reaction of HNO3
with NH3, which is of direct interest for fertilizer application.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 8.4
DOI: 10.1021/acssuschemeng.3c00208
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“Study of the Mechanism and Increasing Crystallinity in the Self-Templated Growth of Ultrathin PbS Nanosheets”. van der Sluijs MM, Salzmann BBV, Arenas Esteban D, Li C, Jannis D, Brafine LC, Laning TD, Reinders JWC, Hijmans NSA, Moes JR, Verbeeck J, Bals S, Vanmaekelbergh D, Chemistry of materials (2023). http://doi.org/10.1021/acs.chemmater.3c00300
Abstract: Colloidal 2D semiconductor nanocrystals, the analogue of solid-state quantum wells, have attracted strong interest in material science and physics. Molar quantities of suspended quantum objects with spectrally pure absorption and emission can be synthesized. For the visible region, CdSe nanoplatelets with atomically precise thickness and tailorable emission have been (almost) perfected. For the near-infrared region, PbS nanosheets (NSs) hold strong promise, but the photoluminescence quantum yield is low and many questions on the crystallinity, atomic structure, intriguing rectangular shape, and formation mechanism remain to be answered. Here, we report on a detailed investigation of the PbS NSs prepared with a lead thiocyanate single source precursor. Atomically resolved HAADF-STEM imaging reveals the presence of defects and small cubic domains in the deformed orthorhombic PbS crystal lattice. Moreover, variations in thickness are observed in the NSs, but only in steps of 2 PbS monolayers. To study the reaction mechanism, a synthesis at a lower temperature allowed for the study of reaction intermediates. Specifically, we studied the evolution of pseudo-crystalline templates towards mature, crystalline PbS NSs. We propose a self-induced templating mechanism based on an oleylamine-lead-thiocyanate (OLAM-Pb-SCN) complex with two Pb-SCN units as a building block; the interactions between the long-chain ligands regulate the crystal structure and possibly the lateral dimensions.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 8.6
Times cited: 2
DOI: 10.1021/acs.chemmater.3c00300
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