“Electrochemical photodegradation study of semiconductor pigments : influence of environmental parameters”. Anaf W, Trashin S, Schalm O, van Dorp D, Janssens K, De Wael K, Analytical chemistry 86, 9742 (2014). http://doi.org/10.1021/AC502303Z
Abstract: Chemical transformations in paintings often induce discolorations, disturbing the appearance of the image. For an appropriate conservation of such valuable and irreplaceable heritage objects, it is important to have a good know-how on the degradation processes of the (historical) materials: which pigments have been discolored, what are the responsible processes, and which (environmental) conditions have the highest impact on the pigment degradation and should be mitigated. Pigment degradation is already widely studied, either by analyzing historical samples or by accelerated weathering experiments on dummies. However, in historic samples several processes may have taken place, increasing the complexity of the current state, while aging experiments are time-consuming due to the often extended aging period. An alternative method is proposed for a fast monitoring of degradation processes of semiconductor pigments, using an electrochemical setup mimicking the real environment and allowing the identification of harmful environmental parameters for each pigment. Examples are given for the pigments cadmium yellow (CdS) and vermilion (α-HgS).
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Cultural Heritage Sciences (ARCHES)
Impact Factor: 6.32
Times cited: 18
DOI: 10.1021/AC502303Z
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“Understanding the (in)stability of semiconductor pigments by a thermodynamic approach”. Anaf W, Schalm O, Janssens K, De Wael K, Dyes and pigments 113, 409 (2015). http://doi.org/10.1016/J.DYEPIG.2014.09.015
Abstract: Several artists pigments are semiconductors. Some of these materials appear stable over time, whereas others already show remarkable signs of degradation after limited time periods. The (in)stability of these pigments can be understood using a thermodynamic approach. For several pigment-related materials, the thermodynamic oxidation and reduction potential (ϕox and ϕred) were determined and evaluated considering the absolute energy positions of the valence and conduction band edges and the water redox potentials. The positions of ϕox and ϕred can be used in a fast screening of the stability of semiconductor pigments towards photoinduced corrosion in an aqueous/humid environment. This theoretical approach corresponds well with experimental data on pigment permanence and degradation phenomena found in literature.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Cultural Heritage Sciences (ARCHES)
Impact Factor: 3.473
Times cited: 14
DOI: 10.1016/J.DYEPIG.2014.09.015
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“Multi-modal approach for the characterization of resin carriers in Daylight Fluorescent Pigments”. Álvarez-Martín A, De Winter S, Nuyts G, Hermans J, Janssens K, van der Snickt G, Microchemical Journal 159, 105340 (2020). http://doi.org/10.1016/J.MICROC.2020.105340
Abstract: Almost seventy years after artists such as Frank Stella (1936), Andy Warhol (1928-1987), James Rosenquist (1933-2017), Herb Aach (1923-1985) and Richard Bowman (1918-2001) started to incorporate Daylight Fluorescent Pigments (DFPs) in their artworks, the extent of the conservation problems that are associated with these pigments has increased progressively. Since their first appearance on the market, their composition has constantly been improved in terms of permanency. However, conservation practices on the artworks that are used in, are complicated by the fact that the composition of DFPs is proprietary and the information provided by the manufactures is limited. To be able to propose adequate conservation strategies for artworks containing DFPs, a thorough understanding of the DFPs composition must be acquired. In contrast with previous research that concentrated on identification of the coloring dye, this paper focuses on the characterization of the resin, used as the carrier for the dye. The proposed approach, involving ATR-FTIR, SPME-GC-MS and XRF analysis, provided additional insights on the organic and inorganic components of the resin. Using this approach, we investigated historical DFPs and new formulations, as well as different series from the main manufacturing companies (DayGlo, Swada, Radiant Color and Kremer) in order to obtain a full characterization of DFPs used by the artists along the years. First, the initial PCA-assisted ATR-FTIR spectroscopy allowed for an efficient classification of the main monomers in the resin polymer. Next, a further distinction was made by mass spectrometry and XRF which were optimized to allow a more specific classification of the resin and for detection of additives. In this paper we show the potential of SPME-GC-MS, never applied for the characterization of artistic materials, at present undervalued for heritage science purposes. We anticipate that this information will be highly relevant in the future stability studies and for defining (preventive) conservation strategies of fluorescent artworks.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Cultural Heritage Sciences (ARCHES)
Impact Factor: 4.8
DOI: 10.1016/J.MICROC.2020.105340
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“Respiratory muscle activity after spontaneous, neostigmine- or sugammadex-enhanced recovery of neuromuscular blockade : a double blind prospective randomized controlled trial”. Schepens T, Janssens K, Maes S, Wildemeersch D, Vellinga J, Jorens PG, Saldien V, BMC anesthesiology 19, 187 (2019). http://doi.org/10.1186/S12871-019-0863-Y
Abstract: Background The use of neostigmine after neuromuscular blockade (NMB) has been associated with postoperative respiratory complications. In previous studies, we found lower diaphragmatic activity after neostigmine reversal of NMB, compared to sugammadex. It is still unclear whether the adequate use of neostigmine guarantees normal respiratory muscle function after NMB. In this study, we wanted to assess the effect of commonly used degrees of NMB and their possible reversal strategies on respiratory muscle activity after the return of normal neuromuscular transmission. Methods This is a randomized, controlled, parallel-group, single-centre, double-blind study in patients scheduled for intracranial surgery at a tertiary academic hospital in Belgium. All participants received target controlled propofol/remifentanil anesthesia and were randomized into one of five groups, receiving either a shallow NMB with no reversal (shallow/saline), a shallow NMB with sugammadex reversal (shallow/sugammadex), a moderate NMB with neostigmine reversal (moderate/neostigmine), a moderate NMB with sugammadex reversal (moderate/sugammadex), or a deep NMB with sugammadex reversal (deep/sugammadex). Primary and secondary outcome parameters were diaphragm and intercostal electromyographic (EMG) activity at the moment of resumed spontaneous breathing activity, defined as a maximal interval of 10 min after the first spontaneous breath. Results For the five groups, a total of 55 patients could be included in the final analysis. Median time of spontaneous breathing analyzed was 5 min (IQR 3-9.5 min). Both the moderate/sugammadex and the moderate/neostigmine groups had lower levels of diaphragm EMG compared to the shallow/sugammadex group. The moderate/neostigmine group had lower levels of intercostal EMG activity compared to the shallow/saline group. Conclusions In this study, the depth of neuromuscular blockade and type of reversal strategy impacts respiratory muscle activity at the moment of resumed spontaneous breathing and recovery of neuromuscular blockade. Both groups that received moderate NMB had lower levels of diaphragm EMG, compared to the shallow NMB group with sugammadex reversal. Compared to the shallow NMB group with no reversal, the moderate NMB with neostigmine reversal group had lower intercostal EMG activity.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Surgical Training, Anatomy and Research Centre (ASTARC); Laboratory Experimental Medicine and Pediatrics (LEMP)
Impact Factor: 1.525
DOI: 10.1186/S12871-019-0863-Y
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“High-resolution mass spectrometry and nontraditional mass defect analysis of brominated historical pigments”. Alvarez-Martin A, Newsome GA, Janssens K, Analytical Chemistry 93, 14851 (2021). http://doi.org/10.1021/ACS.ANALCHEM.1C03815
Abstract: The implementation of high-resolution mass spectrometry systems offers new possibilities for the analysis of complex art samples such as historical oil paintings. However, these multicomponent systems generate large and complex data sets that require advanced visualization tools to aid interpretation, especially when no chromatographic separation is performed. In the context of this research, it was crucial to propose a data analysis tool to identify the products generated during the synthesis, drying, and aging of historical pigments. This study reports for the first time a nontraditional mass defect analysis of oil paint samples containing a fugitive brominated-organic pigment, eosin or geranium lake, by using direct infusion electrospray ionization in combination with a high-resolution Orbitrap mass spectrometer. The use of nontraditional Kendrick mass defect plots is presented in this study as a processing and visualization tool to recognize brominated species based on their specific mass defect and isotope pattern. The results demonstrate that this approach could provide valuable molecular compositional information on the degradation pathways of this pigment. We anticipate that mass defect analysis will become highly relevant in future degradation studies of many more historical organic pigments.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp X-ray Imaging and Spectroscopy (AXIS)
Impact Factor: 6.32
DOI: 10.1021/ACS.ANALCHEM.1C03815
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“A general-purpose interface between fortran and the low-level functions of the ibm-pc”. Janssens K, van Espen P, Trends in analytical chemistry 7, 128 (1988). http://doi.org/10.1016/0165-9936(88)87009-2
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Chemometrics (Mitac 3)
DOI: 10.1016/0165-9936(88)87009-2
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“Analysis of X-ray spectra by iterative least squares (AXIL): new developments”. Vekemans B, Janssens K, Vincze L, Adams F, van Espen P, X-ray spectrometry 23, 278 (1994). http://doi.org/10.1002/XRS.1300230609
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Chemometrics (Mitac 3)
DOI: 10.1002/XRS.1300230609
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“AXIL-PC, software for the analysis of complex-x-ray spectra”. van Espen P, Janssens K, Nobels J, Chemometrics and intelligent laboratory systems 1, 109 (1986). http://doi.org/10.1016/0169-7439(86)80031-4
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Chemometrics (Mitac 3)
DOI: 10.1016/0169-7439(86)80031-4
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“Evaluation of energy-dispersive x-ray-spectra with the aid of expert systems”. Janssens K, van Espen P, Analytica chimica acta 191, 169 (1986). http://doi.org/10.1016/S0003-2670(00)86306-0
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Chemometrics (Mitac 3)
DOI: 10.1016/S0003-2670(00)86306-0
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“Implementation of an expert system for the qualitative interpretation of x-ray-fluorescence spectra”. Janssens K, van Espen P, Analytica chimica acta 184, 117 (1986). http://doi.org/10.1016/S0003-2670(00)86475-2
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Chemometrics (Mitac 3)
DOI: 10.1016/S0003-2670(00)86475-2
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“Increased accuracy in the automated interpretation of large epma data sets by the use of an expert system”. Janssens K, Vanborm W, van Espen P, Journal of research of the National Bureau of Standards (1934) 93, 260 (1988). http://doi.org/10.6028/JRES.093.037
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Chemometrics (Mitac 3)
DOI: 10.6028/JRES.093.037
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“Microanalytical characterization of surface decoration in Majolica pottery”. Padilla R, Schalm O, Janssens K, Arrazcaeta R, van Espen P, Analytica chimica acta 535, 201 (2005). http://doi.org/10.1016/J.ACA.2004.11.082
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Chemometrics (Mitac 3)
Impact Factor: 4.95
Times cited: 20
DOI: 10.1016/J.ACA.2004.11.082
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“Monte Carlo simulation of conventional and synchrotron energy-dispersive X-ray spectrometers”. Janssens K, Vincze L, van Espen P, Adams F, X-ray spectrometry 22, 234 (1993). http://doi.org/10.1002/XRS.1300220412
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Chemometrics (Mitac 3)
DOI: 10.1002/XRS.1300220412
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“PC-MCA : a software package for the acquisition and processing of spectral data”. Janssens K, Nobels J, van Espen P, Chemometrics and intelligent laboratory systems 3, 335 (1988). http://doi.org/10.1016/0169-7439(88)80033-9
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Chemometrics (Mitac 3)
DOI: 10.1016/0169-7439(88)80033-9
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“Quantitative analysis of 16-17th century archaeological glass vessels using PLS regression of EPXMA and μ-XRF data”. Lemberge P, Deraedt I, Janssens K, van Espen P, Journal of chemometrics 14, 751 (2000). http://doi.org/10.1002/1099-128X(200009/12)14:5/6<751::AID-CEM622>3.0.CO;2-D
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Chemometrics (Mitac 3)
Impact Factor: 1.884
DOI: 10.1002/1099-128X(200009/12)14:5/6<751::AID-CEM622>3.0.CO;2-D
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“Semiempirical approach for standardless calibration in µ-XRF spectrometry using capillary lenses”. Padilla R, van Espen P, Abrahantes A, Janssens K, X-ray spectrometry 34, 19 (2005). http://doi.org/10.1002/XRS.781
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Chemometrics (Mitac 3)
Impact Factor: 1.298
Times cited: 23
DOI: 10.1002/XRS.781
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“The development process of an expert system for the automated interpretation of large epma data sets”. Janssens K, Dorrine W, van Espen P, Chemometrics and intelligent laboratory systems 4, 147 (1988). http://doi.org/10.1016/0169-7439(88)80086-8
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Chemometrics (Mitac 3)
DOI: 10.1016/0169-7439(88)80086-8
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“Unraveling the Role of Lattice Substitutions on the Stabilization of the Intrinsically Unstable Pb2Sb2O7Pyrochlore: Explaining the Lightfastness of Lead Pyroantimonate Artists&rsquo, Pigments”. Marchetti A, Saniz R, Krishnan D, Rabbachin L, Nuyts G, De Meyer S, Verbeeck J, Janssens K, Pelosi C, Lamoen D, Partoens B, De Wael K, Chemistry Of Materials 32, 2863 (2020). http://doi.org/10.1021/acs.chemmater.9b04821
Abstract: The pyroantimonate pigments Naples yellow and lead tin antimonate yellow are recognized as some of the most stable synthetic yellow pigments in the history of art. However, this exceptional lightfastness is in contrast with experimental evidence suggesting that this class of mixed oxides is of semiconducting nature. In this study the electronic structure and light-induced behavior of the lead pyroantimonate pigments were determined by means of a combined multifaceted analytical and computational approach (photoelectrochemical measurements, UV-vis diffuse reflectance spectroscopy, STEM-EDS, STEM-HAADF, and density functional theory calculations). The results demonstrate both the semiconducting nature and the lightfastness of these pigments. Poor optical absorption and minority carrier mobility are the main properties responsible for the observed stability. In addition, novel fundamental insights into the role played by Na atoms in the stabilization of the otherwise intrinsically unstable Pb2Sb2O7 pyrochlore were obtained.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
Impact Factor: 8.6
Times cited: 8
DOI: 10.1021/acs.chemmater.9b04821
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“Compositional analysis of 17-18th century archaeological glass fragments, excavated in Mechelen, Belgium: comparison with data from neighboring cities in the Low Countries”. van der Linden V, Bultinck E, de Ruytter J, Schalm O, Janssens K, Devos W, Tiri W, Nuclear instruments and methods in physics research: B: beam interactions with materials and atoms 239, 100 (2005). http://doi.org/10.1016/j.nimb.2005.06.219
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 1.109
Times cited: 15
DOI: 10.1016/j.nimb.2005.06.219
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“Effect of isotropic versus anisotropic elasticity on the electronic structure of cylindrical InP/In0.49Ga0.51P self-assembled quantum dots”. Tadić, M, Peeters FM, Janssens KL, Physical review : B : condensed matter and materials physics 65, 165333 (2002). http://doi.org/10.1103/PhysRevB.65.165333
Abstract: The electronic structure of disk-shaped InP/InGaP self-assembled quantum dots is calculated within the effective-mass theory. The strain-dependent 6x6 multiband Hamiltonian for the valence band is simplified into an axially symmetric form. Both the continuum mechanical model, discretized by finite elements, and the isotropic model are used to calculate the strain distribution and their results are critically compared. The dependence of the electron and the hole energy levels on the dimensions of the quantum dot is investigated. We found that both the electron and hole energies are underestimated if the strain distribution is calculated by the isotropic elasticity theory. The agreement between the electron energies for the two approaches is better for thinner quantum dots. The heavy holes are confined inside the quantum dot, while the light holes are located outside the disk, but confined by the strain field near the edge of the disk periphery. We found that the (h) over bar /2 hole ground state crosses the 3 (h) over bar /2 ground state when the height of the quantum dot increases and becomes the ground state for sufficiently thick quantum disks. The higher hole levels exhibit both crossings between the states of the different parity and anticrossings between the states of the same parity.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 72
DOI: 10.1103/PhysRevB.65.165333
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“Effect of strain on the magnetoexciton ground state in InP/GaxIn1-xP quantum disks”. Janssens KL, Partoens B, Peeters FM, Physical review : B : condensed matter and materials physics 67, 235325 (2003). http://doi.org/10.1103/PhysRevB.67.235325
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 23
DOI: 10.1103/PhysRevB.67.235325
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“Electron and hole localization in coupled InP/InGaP self-assembled quantum dots”. Tadić, M, Peeters FM, Partoens B, Janssens KL, Physica. E: Low-dimensional systems and nanostructures 13, 237 (2002). http://doi.org/10.1016/S1386-9477(01)00528-8
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.221
Times cited: 5
DOI: 10.1016/S1386-9477(01)00528-8
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“Influence of strain on the magneto-exciton in single and coupled InP/GaInP quantum disks”. Janssens KL, Partoens B, Peeters FM, Physica. E: Low-dimensional systems and nanostructures 21, 349 (2004). http://doi.org/10.1016/j.physe.2003.11.269
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.221
DOI: 10.1016/j.physe.2003.11.269
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“Magnetic field dependence of the exciton energy in a quantum disk”. Janssens KL, Peeters FM, Schweigert VA, Physical review : B : condensed matter and materials physics 63, 205311 (2001). http://doi.org/10.1103/PhysRevB.63.205311
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 81
DOI: 10.1103/PhysRevB.63.205311
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“Magnetic field dependence of the properties of excitons confined in a quantum disk”. Janssens KL, Peeters FM, Schweigert VA, Physica status solidi: B: basic research 224, 763 (2001). http://doi.org/10.1002/(SICI)1521-3951(200104)224:3<763::AID-PSSB763>3.0.CO;2-9
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.674
Times cited: 1
DOI: 10.1002/(SICI)1521-3951(200104)224:3<763::AID-PSSB763>3.0.CO;2-9
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“Magnetic field dependence of the xciton energy in type I and type II quantum disks”. Janssens KL, Peeters FM, Schweigert VA, Partoens B, Physica: B : condensed matter 298, 277 (2001). http://doi.org/10.1016/S0921-4526(01)00316-7
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.386
Times cited: 4
DOI: 10.1016/S0921-4526(01)00316-7
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“Magneto-exciton in single and coupled type II quantum dots”. Janssens KL, Partoens B, Peeters FM, Physica status solidi: A: applied research 190, 571 (2002). http://doi.org/10.1002/1521-396X(200204)190:2<571::AID-PSSA571>3.0.CO;2-K
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
DOI: 10.1002/1521-396X(200204)190:2<571::AID-PSSA571>3.0.CO;2-K
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“Magneto-excitons in planar type II quantum dots”. Janssens KL, Partoens B, Peeters FM, Physical review : B : condensed matter and materials physics 64 (2001). http://doi.org/10.1103/PhysRevB.64.155324
Abstract: We study an exciton in a type-II quantum dot, where the electron is confined in the dot, but the hole is located in the barrier material. The exciton properties are studied as a function of a perpendicular magnetic field using a Hartree-Fock mesh calculation. Our model system consists of a planar quantum disk. Angular momentum (l) transitions are predicted with increasing magnetic field. We, also study the transition from a type-I to a type-H quantum dot which is induced by changing the confinement potential of the hole. For sufficiently large magnetic fields a reentrant behavior is found from l(h) = 0 to l(h) not equal 0 and back to l(h) = 0, which results in a transition from type II to type I.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 56
DOI: 10.1103/PhysRevB.64.155324
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“Magnetoexciton in vertically coupled InP/GaInP quantum disks: effect of strain on the exciton ground state”. Janssens KL, Partoens B, Peeters FM, Physical review : B : condensed matter and materials physics 69, 235320 (2004). http://doi.org/10.1103/PhysRevB.69.235320
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 9
DOI: 10.1103/PhysRevB.69.235320
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“Monte-Carlo simulation of the coherent backscattering of electrons in a ballistic system”. Janssens KL, Peeters FM, Superlattices and microstructures 25, 615 (1999). http://doi.org/10.1006/spmi.1999.0697
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.123
DOI: 10.1006/spmi.1999.0697
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