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“Fluid simulation of the superimposed dual-frequency source effect in inductively coupled discharges”. Xiaoyan S, Zhang Y-R, Wang Y-N, He J-X, Physics Of Plasmas 28, 113504 (2021). http://doi.org/10.1063/5.0065438
Abstract: Superimposition of dual frequencies (DFs) is one of the methods used for controlling plasma distribution in an inductively coupled plasma (ICP) source. The effects of a superimposed DF on the argon plasma characteristics have been investigated using a two-dimensional self-consistent fluid model. When both currents are fixed at 6A, the plasma density drops with decrease in one of the source frequencies due to less efficient heating and the plasma uniformity improves significantly. Moreover, for ICP operated with superimposed DFs (i.e., 4.52MHz/13.56MHz and 2.26MHz/13.56MHz), the current source exhibits the same period as the low frequency (LF) component, and the plasma density is higher than that obtained at a single frequency (i.e., 4.52 and 2.26MHz) with the same total current of 12A. However, at superimposed current frequencies of 6.78MHz/13.56MHz, the plasma density is lower than that obtained at a single frequency of 6.78MHz due to the weaker negative azimuthal electric field between two positive maxima during one period of 6.78MHz. When the superimposed DF ICP operates at 2.26 and 13.56MHz, the rapid oscillations of the induced electric field become weaker during one period of 2.26MHz as the current ratio of 2.26MHz/13.56MHz rises from 24A/7 A to 30A/1 A, and the plasma density drops with the current ratio due to weakened electron heating. The uniformity of plasma increases due to sufficient diffusion under the low-density condition.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.115
DOI: 10.1063/5.0065438
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“Ionization and neutral gas heating efficiency in radio frequency electrothermal microthrusters : the role of driving frequency”. Leigh S, Doyle SJ, Smith GJ, Gibson AR, Boswell RW, Charles C, Dedrick JP, Physics of plasmas 31, 023509 (2024). http://doi.org/10.1063/5.0172646
Abstract: The development of compact, low power, charge-neutral propulsion sources is of significant recent interest due to the rising application of micro-scale satellite platforms. Among such sources, radio frequency (rf) electrothermal microthrusters present an attractive option due to their scalability, reliability, and tunable control of power coupling to the propellant. For micropropulsion applications, where available power is limited, it is of particular importance to understand how electrical power can be transferred to the propellant efficiently, a process that is underpinned by the plasma sheath dynamics. In this work, two-dimensional fluid/Monte Carlo simulations are employed to investigate the effects of applied voltage frequency on the electron, ion, and neutral heating in an rf capacitively coupled plasma microthruster operating in argon. Variations in the electron and argon ion densities and power deposition, and their consequent effect on neutral-gas heating, are investigated with relation to the phase-averaged and phase-resolved sheath dynamics for rf voltage frequencies of 6-108 MHz at 450 V. Driving voltage frequencies above 40.68 MHz exhibit enhanced volumetric ionization from bulk electrons at the expense of the ion heating efficiency. Lower driving voltage frequencies below 13.56 MHz exhibit more efficient ionization due to secondary electrons and an increasing fraction of rf power deposition into ions. Thermal efficiencies are improved by a factor of 2.5 at 6 MHz as compared to the more traditional 13.56 MHz, indicating a favorable operating regime for low power satellite applications.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.2
DOI: 10.1063/5.0172646
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“Comparison of electrostatic and electromagnetic simulations for very high frequency plasmas”. Zhang Y-R, Xu X, Zhao S-X, Bogaerts A, Wang Y-N, Physics of plasmas 17, 113512 (2010). http://doi.org/10.1063/1.3519515
Abstract: A two-dimensional self-consistent fluid model combined with the full set of Maxwell equations is developed to investigate an argon capacitively coupled plasma, focusing on the electromagnetic effects on the discharge characteristics at various discharge conditions. The results indicate that there exist distinct differences in plasma characteristics calculated with the so-called electrostatic model (i.e., without taking into account the electromagnetic effects) and the electromagnetic model (which includes the electromagnetic effects), especially at very high frequencies. Indeed, when the excitation source is in the high frequency regime and the electromagnetic effects are taken into account, the plasma density increases significantly and meanwhile the ionization rate evolves to a very different distribution when the electromagnetic effects are dominant. Furthermore, the dependence of the plasma characteristics on the voltage and pressure is also investigated, at constant frequency. It is observed that when the voltage is low, the difference between these two models becomes more obvious than at higher voltages. As the pressure increases, the plasma density profiles obtained from the electromagnetic model smoothly shift from edge-peaked over uniform to a broad maximum in the center. In addition, the edge effect becomes less pronounced with increasing frequency and pressure, and the skin effect rather than the standing-wave effect becomes dominant when the voltage is high.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.115
Times cited: 30
DOI: 10.1063/1.3519515
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“Dispersion relations for circular single and double dusty plasma chains”. Tkachenko DV, Sheridan TE, Misko VR, Physics of plasmas 18, 103709 (2011). http://doi.org/10.1063/1.3651194
Abstract: We derive dispersion relations for a system of identical particles confined in a two-dimensional annular harmonic well and which interact through a Yukawa potential, e.g., a dusty plasma ring. When the particles are in a single chain (i.e., a one-dimensional ring), we find a longitudinal acoustic mode and a transverse optical mode which show approximate agreement with the dispersion relation for a straight configuration for large radii of the ring. When the radius decreases, the dispersion relations modify: there appears an anticrossing of the modes near the crossing point resulting in a frequency gap between the lower and upper branches of the modified dispersion relations. For the double chain (i.e., a two-dimensional zigzag configuration), the dispersion relation has four branches: longitudinal acoustic and optical and transverse acoustic and optical.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.115
Times cited: 7
DOI: 10.1063/1.3651194
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“Electron acceleration by an intense short-pulse laser in underdense plasma”. Yu MY, Yu W, Chen ZY, Zhang J, Yin Y, Cao LH, Lu PX, Xu ZZ, Physics of plasmas 10, 2468 (2003). http://doi.org/10.1063/1.1572158
Abstract: Electron acceleration from the interaction of an intense short-pulse laser with low density plasma is considered. The relation between direct electron acceleration within the laser pulse and that in the wake is investigated analytically. The magnitude and location of the ponderomotive-force-caused charge separation field with respect to that of the pulse determine the relative effectiveness of the two acceleration mechanisms. It is shown that there is an optimum condition for acceleration in the wake. Electron acceleration within the pulse dominates as the pulse becomes sufficiently short, and the latter directly drives and even traps the electrons. The latter can reach ultrahigh energies and can be extracted by impinging the pulse on a solid target. (C) 2003 American Institute of Physics.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.115
Times cited: 41
DOI: 10.1063/1.1572158
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“Electrostatic modes in multi-ion and pair-ion collisional plasmas”. Vranjes J, Petrovic D, Pandey BP, Poedts S, Physics of plasmas 15, 072104 (2008). http://doi.org/10.1063/1.2949696
Abstract: The physics of plasmas containing positive and negative ions is discussed with special attention to the recently produced pair-ion plasma containing ions of equal mass and opposite charge. The effects of the density gradient in the direction perpendicular to the ambient magnetic field vector are discussed. The possible presence of electrons is discussed in the context of plasma modes propagating at an angle with respect to the magnetic field vector. It is shown that the electron plasma mode may become a backward mode in the presence of a density gradient, and this behavior may be controlled either by the electron number density or the mode number in the perpendicular direction. In plasmas with hot electrons an instability may develop, driven by the combination of electron collisions and the density gradient, and in the regime of a sound ions' response. In the case of a pure pair-ion plasma, for lower frequencies and for parameters close to those used in the recent experiments, the perturbed ions may feel the effects of the magnetic field. In this case the plasma mode also becomes backward, resembling features of an experimentally observed but yet unexplained backward mode. (C) 2008 American Institute of Physics.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.115
Times cited: 54
DOI: 10.1063/1.2949696
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“Fluid simulations of frequency effects on nonlinear harmonics in inductively coupled plasma”. Si X-J, Zhao S-X, Xu X, Bogaerts A, Wang Y-N, Physics of plasmas 18, 033504 (2011). http://doi.org/10.1063/1.3566007
Abstract: A fluid model is self-consistently established to investigate the harmonic effects in an inductively coupled plasma, where the electromagnetic field is solved by the finite difference time domain technique. The spatiotemporal distribution of harmonic current density, harmonic potential, and other plasma quantities, such as radio frequency power deposition, plasma density, and electron temperature, have been investigated. Distinct differences in current density have been observed when calculated with and without Lorentz force, which indicates that the nonlinear Lorentz force plays an important role in the harmonic effects, especially at low frequencies. Moreover, the even harmonics are larger than the odd harmonics both in the current density and the potential. Finally, the dependence of various plasma quantities with and without the Lorentz force on various driving frequencies is also examined. It is shown that the deposited power density decreases and the depth of penetration increases slightly because of the Lorentz force. The electron density increases distinctly while the electron temperature remains almost the same when the Lorentz force is taken into account.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.115
Times cited: 7
DOI: 10.1063/1.3566007
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“Perturbation of collisional plasma flow around a charged dust particle: kinetic analysis”. Schweigert IV, Schweigert VA, Peeters FM, Physics of plasmas 12, 113501 (2005). http://doi.org/10.1063/1.2076527
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.115
Times cited: 15
DOI: 10.1063/1.2076527
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“Short-pulse laser absorption in very steep plasma density gradients”. Cai H-bo, Yu W, Zhu S-ping, Zheng C-yang, Cao L-hua, Li B, Chen ZY, Bogaerts A, Physics of plasmas 13, 094504 (2006). http://doi.org/10.1063/1.2354583
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.115
Times cited: 17
DOI: 10.1063/1.2354583
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“Simulation of disk- and band-like voids in dusty plasma systems”. Liu YH, Chen ZY, Huang F, Yu MY, Wang L, Bogaerts A, Physics of plasmas 13, 052110 (2006). http://doi.org/10.1063/1.2201058
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.115
Times cited: 20
DOI: 10.1063/1.2201058
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“Prediction of the decomposition tendency of C5F10O on discharged metal surfaces”. Cui Z, Jafarzadeh A, Hao Y, Liu L, Li L, Zheng Y, IEEE transactions on dielectrics and electrical insulation 30, 1365 (2023). http://doi.org/10.1109/TDEI.2023.3263129
Abstract: In this letter, a dipole sheet method is proposed to theoretically study the adsorption and decomposition of C5F10O over-discharged Cu (111) and Al (111) surfaces. A synergistic effect of external electric fields and surface excess charges shows up for jointly promoting the adsorption of C5F10O, accompanied by the enhancement of C-F bond elongation and charge transfer process. The decomposition of C5F10O is facilitated in the discharged region and the initial decomposition is found most likely to occur via the cleavage of the C-F single bond. The results indicate that the decomposition of C5F10O over the metal electrode surfaces is much accelerated when discharge faults occur and free F atoms could be generated from C5F10O before its carbon chain breakage. These findings help to elucidate the underlying decomposition tendency of C5F10O in discharged systems and provide a practical method for evaluating and designing new insulation gases.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.1
DOI: 10.1109/TDEI.2023.3263129
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“Enthalpy model for heating, melting, and vaporization in laser ablation”. Alexiades V, Autrique D, Electronic journal of differential equations , 1 (2010)
Abstract: Laser ablation is used in a growing number of applications in various areas including medicine, archaeology, chemistry, environmental and materials sciences. In this work the heat transfer and phase change phenomena during nanosecond laser ablation of a copper (Cu) target in a helium (He) background gas at atmospheric pressure are presented. An enthalpy model is outlined, which accounts for heating, melting, and vaporization of the target. As far as we know, this is the first model that connects the thermodynamics and underlying kinetics of this challenging phase change problem in a selfconsistent way.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
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“The Robin problem for the Helmholtz equation in a starlike planar domain”. Caratelli D, Gielis J, Natalini P, Ricci PE, Tavkhelidze I, Georgian mathematical journal 18, 465 (2011). http://doi.org/10.1515/GMJ.2011.0031
Abstract: The interior and exterior Robin problems for the Helmholtz equation in starlike planar domains are addressed by using a suitable Fourier-like technique. Attention is in particular focused on normal-polar domains whose boundaries are defined by the so-called superformula introduced by J. Gielis. A dedicated numerical procedure based on the computer algebra system Mathematica© is developed in order to validate the proposed approach. In this way, highly accurate approximations of the solution, featuring properties similar to the classical ones, are obtained. The computed results are found to be in good agreement with the theoretical findings on Fourier series expansion presented by L. Carleson.
Keywords: A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1515/GMJ.2011.0031
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“Precipitation behaviors in Ti-2.3 Wt Pct Cu alloy during isothermal and two-step aging”. Akamine H, Mitsuhara M, Nishida M, Samaee V, Schryvers D, Tsukamoto G, Kunieda T, Fujii H, Metallurgical And Materials Transactions A-Physical Metallurgy And Materials Science 52, 2760 (2021). http://doi.org/10.1007/S11661-021-06265-X
Abstract: Time evolution of precipitates related to age-hardening in Ti-2.3 wt pct Cu alloys was investigated by electron microscopy. In isothermal aging at 723 K, the hardness increases continuously owing to precipitation strengthening, whereas in two-step aging where the aging temperature is switched from 673 K to 873 K after 100 hours, the hardness is found to drastically drop after the aging temperature switches. In isothermal aging, metastable and stable precipitates are independently nucleated, whereas characteristic V-shaped clusters of precipitates are observed during the two-step aging. It is revealed by atomic-scale observations that the V-shaped clusters are composed of metastable and stable precipitates and each type of precipitate has a different orientation relationship with the alpha phase: (10 (3) over bar)//(0001)(alpha) and [0 (1) over bar0]//respectively. The drop in hardness during two-step aging can be explained by a synergistic effect of decreased precipitation strengthening and solid solution strengthening. (C) The Minerals, Metals & Materials Society and ASM International 2021
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 1.874
DOI: 10.1007/S11661-021-06265-X
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“Comparative study of organic dyes with time-of-flight static secondary ion mass spectrometry and related techniques”. Adriaensen L, Vangaever F, Lenaerts J, Gijbels R, Journal of mass spectrometry 40, 615 (2005). http://doi.org/10.1002/jms.832
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.422
Times cited: 4
DOI: 10.1002/jms.832
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“Low Loss Atomic Layer Deposited Al2O3 Waveguides for Applications in On-Chip Optical Amplifiers”. Demirtas M, Odaci C, Perkgoz NK, Sevik C, Ay F, IEEE journal of selected topics in quantum electronics 24, 3100508 (2018). http://doi.org/10.1109/JSTQE.2018.2825880
Abstract: We present the growth and optimization of ultralow loss Si-based Al2O3 planar waveguides, which have a high potential to boost the performance of rare-earth ion doped waveguide devices operating at visible and C-band wavelength ranges. The planar waveguide structures are grown using thermal atomic layer deposition. Systematic characterization of the obtained thin films is performed by spectroscopic ellipsometry, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy analyses, and the optimum parameters are identified. The optical loss measurements for both transverse electric (TE) and transverse magnetic polarized light at 633, 829, and 1549 nm are performed. The lowest propagation loss value of 0.04 +/- 0.02 dB/cm for the Al2O3 waveguides for TE polarization at 1549 nm is demonstrated.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
DOI: 10.1109/JSTQE.2018.2825880
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“Zitterbewegung of moiré, excitons in twisted MoS₂/WSe₂, heterobilayers”. Lavor IR, da Costa DR, Covaci L, Milošević, MV, Peeters FM, Chaves A, Physical review letters 127, 106801 (2021). http://doi.org/10.1103/PHYSREVLETT.127.106801
Abstract: The moire pattern observed in stacked noncommensurate crystal lattices, such as heterobilayers of transition metal dichalcogenides, produces a periodic modulation of their band gap. Excitons subjected to this potential landscape exhibit a band structure that gives rise to a quasiparticle dubbed the moire exciton. In the case of MoS2/WSe2 heterobilayers, the moire trapping potential has honeycomb symmetry and, consequently, the moire exciton band structure is the same as that of a Dirac-Weyl fermion, whose mass can be further tuned down to zero with a perpendicularly applied field. Here we show that, analogously to other Dirac-like particles, the moire exciton exhibits a trembling motion, also known as Zitterbewegung, whose long timescales are compatible with current experimental techniques for exciton dynamics. This promotes the study of the dynamics of moire excitons in van der Waals heterostructures as an advantageous solid-state platform to probe Zitterbewegung, broadly tunable by gating and interlayer twist angle.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
Times cited: 5
DOI: 10.1103/PHYSREVLETT.127.106801
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“Dynamic identifiability analysis-based model structure evaluation considering rating curve uncertainty”. Van Hoey S, Nopens I, van der Kwast J, Seuntjens P, Journal of hydrologic engineering 20, 04014072 (2015). http://doi.org/10.1061/(ASCE)HE.1943-5584.0000995
Abstract: When applying hydrological models, different sources of uncertainty are present, and evaluations of model performances should take these into account to assess model outcomes correctly. Furthermore, uncertainty in the discharge observations complicates the model identification, both in terms of model structure and parameterization. In this paper, the authors compare two different lumped model structures (PDM and NAM) considering uncertainty coming from the rating curve. Limits of acceptability for the model simulations were determined based on derived uncertainty bounds of the discharge observations. The authors applied the DYNamic Identifiability Approach (DYNIA) to identify structural failure of both models and to evaluate the configuration of their structures. In general, similar model performances are observed. However, the model structures tend to behave differently in the course of time, as revealed by the DYNIA approach. Based on the analyses performed, the probability based soil storage representation of the PDM model outperforms the NAM structure. The incorporation of the observation error did not prevent the DYNIA analysis to identify potential model structural deficiencies that are limiting the representation of the seasonal variation, primarily indicated by shifting regions of parameter identifiability. As such, the proposed approach is able to indicate where deficiencies are found and model improvement is needed.
Keywords: A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1061/(ASCE)HE.1943-5584.0000995
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“From olivine to ringwoodite : a TEM study of a complex process”. Pittarello L, Ji G, Yamaguchi A, Schryvers D, Debaille V, Claeys P, Meteoritics and Planetary Science 50, 944 (2015). http://doi.org/10.1111/maps.12441
Abstract: The study of shock metamorphism of olivine might help to constrain impact events in the history of meteorites. Although shock features in olivine are well known, so far, there are processes that are not yet completely understood. In shock veins, olivine clasts with a complex structure, with a ringwoodite rim and a dense network of lamellae of unidentified nature in the core, have been reported in the literature. A highly shocked (S5-6), L6 meteorite, Asuka 09584, which was recently collected in Antarctica by a Belgian-Japanese joint expedition, contains this type of shocked olivine clasts and has been, therefore, selected for detailed investigations of these features by transmission electron microscopy (TEM). Petrographic, geochemical, and crystallographic studies showed that the rim of these shocked clasts consists of an aggregate of nanocrystals of ringwoodite, with lower Mg/Fe ratio than the unshocked olivine. The clast's core consists of an aggregate of iso-oriented grains of olivine and wadsleyite, with higher Mg/Fe ratio than the unshocked olivine. This aggregate is crosscut by veinlets of nanocrystals of olivine, with extremely low Mg/Fe ratio. The formation of the ringwoodite rim is likely due to solid-state, diffusion-controlled, transformation from olivine under high-temperature conditions. The aggregate of iso-oriented olivine and wadsleyite crystals is interpreted to have formed also by a solid-state process, likely by coherent intracrystalline nucleation. Following the compression, shock release is believed to have caused opening of cracks and fractures in olivine and formation of olivine melt, which has lately crystallized under postshock equilibrium pressure conditions as olivine.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.391
Times cited: 8
DOI: 10.1111/maps.12441
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“Novel imaging techniques using computer methods for the evaluation of the upper airway in patients with sleep-disordered breathing: a comprehensive review”. de Backer JW, Vos WG, Verhulst SL, de Backer W, Sleep medicine reviews 12, 437 (2008). http://doi.org/10.1016/j.smrv.2008.07.009
Abstract: Patients with sleep related breathing disorders (SRBD) can be treated with nasal continuous positive airway pressure (nCPAP) or with several upper airway (UA) interventions. While nCPAP is almost always effective when clinically well tolerated, the therapeutic outcome of UA surgery and UA devices is difficult to predict. The improvement of our capability to perform the latter predictions more accurately is of great clinical importance since it will prevent patients to be treated with ineffective, sometimes irreversible, techniques. In this review we describe the importance of new imaging methods in this respect. We first refer to the most important pathophysiological mechanisms known so far to play a role in SRBD, indicating that functional imaging could elucidate these mechanisms in a patient specific manner. Then we describe the new technologies that make UA imaging more functional referring to the data as they are presently available. Finally we summarise the studies that do indicate that the use of functional imaging of the UA in SRBD patients may significantly help to predict the clinical outcome after UA interventions.
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Laboratory Experimental Medicine and Pediatrics (LEMP)
Impact Factor: 8.958
Times cited: 33
DOI: 10.1016/j.smrv.2008.07.009
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“Distribution pattern of metal atoms in bimetal-doped pyridinic-N₄, pores determines their potential for electrocatalytic N₂, reduction”. Nematollahi P, Neyts EC, Journal Of Physical Chemistry A 126, 3080 (2022). http://doi.org/10.1021/ACS.JPCA.2C00486
Abstract: Doping two single transition-metal (TM) atoms on a substrate host opens numerous possibilities for catalyst design. However, what if the substrate contains more than one vacancy site? Then, the combination of two TMs along with their distribution patterns becomes a design parameter potentially complementary to the substrate itself and the bimetal composition. In this study, we investigate ammonia synthesis under mild electrocatalytic conditions on a transition-metal-doped porous C24N24 catalyst using density functional theory (DFT). The TMs studied include Ti, Mn, and Cu in a 2:4 dopant ratio (Ti2Mn4@C24N24 and Ti2Cu4@N-24(24)). Our computations show that a single Ti atom in both catalysts exhibits the highest selectivity for N-2 fixation at ambient conditions. This work is a good theoretical model to establish the structure-activity relationship, and the knowledge earned from the metal-N-4 moieties may help studies of related nanomaterials, especially those with curved structures.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.9
DOI: 10.1021/ACS.JPCA.2C00486
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“Comparative study of structural properties and photoluminescence in InGaN layers with a high In content”. Vantomme A, Wu MF, Hogg S, van Landuyt J, et al, Internet journal of nitride semiconductor research
T2 –, Symposium on GaN and Related Alloys Held at the MRS Fall Meeting, NOV 29-DEC 03, 1999, BOSTON, MASSACHUSETTS 5, art. no.-W11.38 (2000)
Abstract: Rutherford backscattering and channeling spectrometry (RBS), photoluminescence (PL) spectroscopy and transmission electron microscopy (TEM) have been used to investigate macroscopic and microscopic segregation in MOCVD grown InGaN layers. The PL peak energy and In content (measured by RES) were mapped at a large number of distinct points on the samples. An indium concentration of 40%, the highest measured in this work, corresponds to a PL peak of 710 nn strongly suggesting that the light-emitting regions of the sample me very indium-rich compared to the average measured by RES. Cross-sectional TEM observations show distinctive layering of the InGaN films. The TEM study further reveals that these layers consist of amorphous pyramidal contrast features with sizes of order 10 nm The composition of these specific contrast features is shown to be In-rich compared to the nitride matrix.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
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“Modeling of the synthesis and subsequent growth of nanoparticles in dusty plasmas”. de Bleecker K, Bogaerts A, High temperature material processes 11, 21 (2007). http://doi.org/10.1615/HighTempMatProc.v11.i1.20
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
DOI: 10.1615/HighTempMatProc.v11.i1.20
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“Modeling PECVD growth of nanostructured carbon materials”. Neyts E, Bogaerts A, van de Sanden MCM, High temperature material processes 13, 399 (2009). http://doi.org/10.1615/HighTempMatProc.v13.i3-4.120
Abstract: We present here some of our modeling efforts for PECVD growth of nanostructured carbon materials with focus on amorphous hydrogenated carbon. Experimental data from an expanding thermal plasma setup were used as input for the simulations. Attention was focused both on the film growth mechanism, as well as on the hydrocarbon reaction mechanisms during growth of the films. It is found that the reaction mechanisms and sticking coefficients are dependent on the specific surface sites, and the structural properties of the growth radicals. The film growth results are in correspondence with the experiment. Furthermore, it is found that thin a-C:H films can be densified using an additional H-flux towards the substrate.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
DOI: 10.1615/HighTempMatProc.v13.i3-4.120
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“Numerical modeling for a better understanding of gas discharge plasmas”. Bogaerts A, de Bleecker K, Georgieva V, Herrebout D, Kolev I, Madani M, Neyts E, High temperature material processes 9, 321 (2005). http://doi.org/10.1615/HighTempMatProc.v9.i3.10
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Times cited: 1
DOI: 10.1615/HighTempMatProc.v9.i3.10
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“Kinetic exploration of intracellular nitrate storage in marine microalgae”. Decostere B, Coppens J, Vervaeren H, Vlaeminck SE, De Gelder L, Boon N, Nopens I, Van Hulle SWH, Journal of environmental science and health : part A: toxic/hazardous substances and environmental engineering 52, 1303 (2017). http://doi.org/10.1080/10934529.2017.1364921
Abstract: In this study, a recently developed model accounting for intracellular nitrate storage kinetics was thoroughly studied to understand and compare the storage capacity of Phaeodactylum tricornutum and Amphora coffeaeformis. In the first stage the identifiability of the biokinetic parameters was examined. Next, the kinetic model was calibrated for both microalgal species based on experimental observations during batch growth experiments. Two kinetic parameters were calibrated, namely the maximum specific growth rate (mu(max)) and the nitrate storage rate (k(sto)). A significant difference was observed for the nitrate storage rate between both species. For P. tricornutum, the nitrate storage rate was much higher (k(sto) = 0.036m(3) g(-1) DW d(-1)) compared to A. coffeaeformis (k(sto) = 0.0004m(3) g(-1) DW d(-1)). This suggests that P. tricornutum has a more efficient nitrate uptake ability and intracellular nitrate storage capacity and also indicates the need for determination of k(sto) in order to quantify nitrate storage.
Keywords: A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1080/10934529.2017.1364921
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“Quench dynamics of an ultracold Fermi gas in the BCS regime : spectral properties and confinement-induced breakdown of the Higgs mode”. Hannibal S, Kettmann P, Croitoru MD, Vagov A, Axt VM, Kuhn T, Physical review : A : atomic, molecular and optical physics 91, 043630 (2015). http://doi.org/10.1103/PhysRevA.91.043630
Abstract: The Higgs amplitude mode of the order parameter of an ultracold confined Fermi gas in the BCS regime after a quench of the coupling constant is analyzed theoretically. A characteristic feature is a damped oscillation which at a certain transition time changes into a rather irregular dynamics. We compare the numerical solution of the full set of nonlinear equations of motion for the normal and anomalous Bogoliubov quasiparticle excitations with a linearized approximation. In doing so the transition time as well as the difference between resonant systems, i.e., systems where the Fermi energy is close to a sub-band minimum, and off-resonant systems can be well understood and traced back to the system and geometry parameters.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.925
Times cited: 10
DOI: 10.1103/PhysRevA.91.043630
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“Optical enhancement of a printed organic tandem solar cell using diffractive nanostructures”. Mayer JA, Offermans T, Chrapa M, Pfannmöller M, Bals S, Ferrini R, Nisato G, Optics express 26, A240 (2018). http://doi.org/10.1364/OE.26.00A240
Abstract: Solution processable organic tandem solar cells offer a promising approach to achieve cost-effective, lightweight and flexible photovoltaics. In order to further enhance the efficiency of optimized organic tandem cells, diffractive light-management nanostructures were designed for an optimal redistribution of the light as function of both wavelength and propagation angles in both sub-cells. As the fabrication of these optical structures is compatible with roll-to-roll production techniques such as hot-embossing or UV NIL imprinting, they present an optimal cost-effective solution for printed photovoltaics. Tandem cells with power conversion efficiencies of 8-10% were fabricated in the ambient atmosphere by doctor blade coating, selected to approximate the conditions during roll-to-roll manufacturing. Application of the light management structure onto an 8.7% efficient encapsulated tandem cell boosted the conversion efficiency of the cell to 9.5%. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.307
Times cited: 9
DOI: 10.1364/OE.26.00A240
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“Electrical generation of terahertz blackbody radiation from graphene”. Dong HM, Xu W, Peeters FM, Optics express 26, 24621 (2018). http://doi.org/10.1364/OE.26.024621
Abstract: Recent experimental work on the application of graphene for novel illumination motivated us to present a theoretical study of the blackbody radiation emission from a freely suspended graphene driven by a dc electric field. Strong terahertz (THz) emission, with intensity up to mW/cm(2), can be generated with increasing electric field strength due to the heating of electrons in graphene. We show that the intensity of the THz emission generated electrically from graphene depends rather sensitively on the lattice temperature in relatively weak electric fields, whereas it is less sensitive to the lattice temperature in relative strong electric fields. Our study highlights the practical application of graphene as intense THz source where the radiation is generated electrically. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.307
Times cited: 14
DOI: 10.1364/OE.26.024621
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“Linearized radially polarized light for improved precision in strain measurements using micro-Raman spectroscopy”. Prabhakara V, Nuytten T, Bender H, Vandervorst W, Bals S, Verbeeck J, Optics Express 29, 34531 (2021). http://doi.org/10.1364/OE.434726
Abstract: Strain engineering in semiconductor transistor devices has become vital in the semiconductor industry due to the ever-increasing need for performance enhancement at the nanoscale. Raman spectroscopy is a non-invasive measurement technique with high sensitivity to mechanical stress that does not require any special sample preparation procedures in comparison to characterization involving transmission electron microscopy (TEM), making it suitable for inline strain measurement in the semiconductor industry. Indeed, at present, strain measurements using Raman spectroscopy are already routinely carried out in semiconductor devices as it is cost effective, fast and non-destructive. In this paper we explore the usage of linearized radially polarized light as an excitation source, which does provide significantly enhanced accuracy and precision as compared to linearly polarized light for this application. Numerical simulations are done to quantitatively evaluate the electric field intensities that contribute to this enhanced sensitivity. We benchmark the experimental results against TEM diffraction-based techniques like nano-beam diffraction and Bessel diffraction. Differences between both approaches are assigned to strain relaxation due to sample thinning required in TEM setups, demonstrating the benefit of Raman for nondestructive inline testing.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.307
Times cited: 2
DOI: 10.1364/OE.434726
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