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Teurtrie A, Perraudin N, Holvoet T, Chen H, Alexander DTL, Obozinski G, Hébert C. espm: A Python library for the simulation of STEM-EDXS datasets. Ultramicroscopy 2023; 249:113719. [PMID: 37003127 DOI: 10.1016/j.ultramic.2023.113719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 03/09/2023] [Accepted: 03/14/2023] [Indexed: 04/01/2023]
Abstract
We present two open-source Python packages: "electron spectro-microscopy" (espm) and "electron microscopy tables" (emtables). The espm software enables the simulation of scanning transmission electron microscopy energy-dispersive X-ray spectroscopy datacubes, based on user-defined chemical compositions and spatial abundance maps of constituent phases. The simulation process uses X-ray emission cross-sections generated via state-of-the-art calculations made with emtables. These tables are designed to be easily modifiable, either manually or using espm. The simulation framework is designed to test the application of decomposition algorithms for the analysis of STEM-EDX spectrum images with access to a known ground truth. We validate our approach using the case of a complex geology-related sample, comparing raw simulated and experimental datasets and the outputs of their non-negative matrix factorization. In addition to testing machine learning algorithms, our packages will also help experimental design, for instance, predicting dataset characteristics or establishing minimum counts needed to measure nanoscale features.
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Affiliation(s)
- Adrien Teurtrie
- Electron Spectrometry and Microscopy Laboratory, Institute of Physics (IPHYS), École Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland; Unité Matériaux et Transformations, UMR-CNRS 8207, Université de Lille, Cité scientifique, Bâtiment C6, 59655, Villeneuve d'Ascq, France
| | - Nathanaël Perraudin
- Swiss Data Science Center, EPFL & ETH Zürich, Turnerstrasse 1, 8092, Zürich, Switzerland
| | - Thomas Holvoet
- Swiss Data Science Center, EPFL & ETH Zürich, Turnerstrasse 1, 8092, Zürich, Switzerland
| | - Hui Chen
- Electron Spectrometry and Microscopy Laboratory, Institute of Physics (IPHYS), École Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland
| | - Duncan T L Alexander
- Electron Spectrometry and Microscopy Laboratory, Institute of Physics (IPHYS), École Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland
| | - Guillaume Obozinski
- Swiss Data Science Center, EPFL & ETH Zürich, Turnerstrasse 1, 8092, Zürich, Switzerland
| | - Cécile Hébert
- Electron Spectrometry and Microscopy Laboratory, Institute of Physics (IPHYS), École Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland; Institute of Materials (IMX), École Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland.
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2
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Nabiei F, Badro J, Boukaré C, Hébert C, Cantoni M, Borensztajn S, Wehr N, Gillet P. Investigating Magma Ocean Solidification on Earth Through Laser-Heated Diamond Anvil Cell Experiments. Geophys Res Lett 2021; 48:e2021GL092446. [PMID: 34219835 PMCID: PMC8244043 DOI: 10.1029/2021gl092446] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 05/18/2021] [Accepted: 05/22/2021] [Indexed: 05/09/2023]
Abstract
We carried out a series of silicate fractional crystallization experiments at lower mantle pressures using the laser-heated diamond anvil cell. Phase relations and the compositional evolution of the cotectic melt and equilibrium solids along the liquid line of descent were determined and used to assemble the melting phase diagram. In a pyrolitic magma ocean, the first mineral to crystallize in the deep mantle is iron-depleted calcium-bearing bridgmanite. From the phase diagram, we estimate that the initial 33%-36% of the magma ocean will crystallize to form such a buoyant bridgmanite. Substantial calcium solubility in bridgmanite is observed up to 129 GPa, and significantly delays the crystallization of the calcium silicate perovskite phase during magma ocean solidification. Residual melts are strongly iron-enriched as crystallization proceeds, making them denser than any of the coexisting solids at deep mantle conditions, thus supporting the terrestrial basal magma ocean hypothesis (Labrosse et al., 2007).
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Affiliation(s)
- Farhang Nabiei
- Earth and Planetary Science LaboratoryEPFLLausanneSwitzerland
- Electron Spectrometry and Microscopy LaboratoryEPFLLausanneSwitzerland
| | - James Badro
- Earth and Planetary Science LaboratoryEPFLLausanneSwitzerland
- Université de ParisInstitut de Physique du Globe de ParisCNRSParisFrance
| | - Charles‐Édouard Boukaré
- Earth and Planetary Science LaboratoryEPFLLausanneSwitzerland
- Université de ParisInstitut de Physique du Globe de ParisCNRSParisFrance
| | - Cécile Hébert
- Electron Spectrometry and Microscopy LaboratoryEPFLLausanneSwitzerland
| | - Marco Cantoni
- Interdisciplinary Centre for Electron MicroscopyEPFLLausanneSwitzerland
| | | | - Nicolas Wehr
- Université de ParisInstitut de Physique du Globe de ParisCNRSParisFrance
| | - Philippe Gillet
- Earth and Planetary Science LaboratoryEPFLLausanneSwitzerland
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3
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Zamani M, Imbalzano G, Tappy N, Alexander DTL, Martí-Sánchez S, Ghisalberti L, Ramasse QM, Friedl M, Tütüncüoglu G, Francaviglia L, Bienvenue S, Hébert C, Arbiol J, Ceriotti M, Fontcuberta I Morral A. 3D Ordering at the Liquid-Solid Polar Interface of Nanowires. Adv Mater 2020; 32:e2001030. [PMID: 32762011 DOI: 10.1002/adma.202001030] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 06/29/2020] [Indexed: 06/11/2023]
Abstract
The nature of the liquid-solid interface determines the characteristics of a variety of physical phenomena, including catalysis, electrochemistry, lubrication, and crystal growth. Most of the established models for crystal growth are based on macroscopic thermodynamics, neglecting the atomistic nature of the liquid-solid interface. Here, experimental observations and molecular dynamics simulations are employed to identify the 3D nature of an atomic-scale ordering of liquid Ga in contact with solid GaAs in a nanowire growth configuration. An interplay between the liquid ordering and the formation of a new bilayer is revealed, which, contrary to the established theories, suggests that the preference for a certain polarity and polytypism is influenced by the atomic structure of the interface. The conclusions of this work open new avenues for the understanding of crystal growth, as well as other processes and systems involving a liquid-solid interface.
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Affiliation(s)
- Mahdi Zamani
- Laboratory of Semiconductor Materials, Institute of Materials, Faculty of Engineering, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
| | - Giulio Imbalzano
- Laboratory of Computational Science and Modeling, Institute of Materials, Faculty of Engineering, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
| | - Nicolas Tappy
- Laboratory of Semiconductor Materials, Institute of Materials, Faculty of Engineering, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
| | - Duncan T L Alexander
- Electron Spectrometry and Microscopy Laboratory, Institute of Physics, Faculty of Basic Sciences, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
- Interdisciplinary Centre for Electron Microscopy (CIME), École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
| | - Sara Martí-Sánchez
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona, Catalonia, 08193, Spain
| | - Lea Ghisalberti
- Laboratory of Semiconductor Materials, Institute of Materials, Faculty of Engineering, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
| | - Quentin M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Keckwick Lane, Daresbury, WA4 4AD, UK
- School of Chemical and Process Engineering and School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
| | - Martin Friedl
- Laboratory of Semiconductor Materials, Institute of Materials, Faculty of Engineering, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
| | - Gözde Tütüncüoglu
- Laboratory of Semiconductor Materials, Institute of Materials, Faculty of Engineering, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
| | - Luca Francaviglia
- Laboratory of Semiconductor Materials, Institute of Materials, Faculty of Engineering, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
| | - Sebastien Bienvenue
- Laboratory of Computational Science and Modeling, Institute of Materials, Faculty of Engineering, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
| | - Cécile Hébert
- Electron Spectrometry and Microscopy Laboratory, Institute of Physics, Faculty of Basic Sciences, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
- Institute of Materials, Faculty of Engineering, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
| | - Jordi Arbiol
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona, Catalonia, 08193, Spain
- ICREA, Pg. Lluís Companys 23, Barcelona, Catalonia, 08010, Spain
| | - Michele Ceriotti
- Laboratory of Computational Science and Modeling, Institute of Materials, Faculty of Engineering, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
| | - Anna Fontcuberta I Morral
- Laboratory of Semiconductor Materials, Institute of Materials, Faculty of Engineering, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
- Institute of Physics, Faculty of Basic Sciences, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
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4
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Oveisi E, Spadaro MC, Rotunno E, Grillo V, Hébert C. Insights into image contrast from dislocations in ADF-STEM. Ultramicroscopy 2019; 200:139-148. [PMID: 30925259 DOI: 10.1016/j.ultramic.2019.02.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 01/02/2019] [Accepted: 02/06/2019] [Indexed: 10/27/2022]
Abstract
Competitive mechanisms contribute to image contrast from dislocations in annular dark-field scanning transmission electron microscopy (ADF-STEM). A clear theoretical understanding of the mechanisms underlying the ADF-STEM contrast is therefore essential for correct interpretation of dislocation images. This paper reports on a systematic study of the ADF-STEM contrast from dislocations in a GaN specimen, both experimentally and computationally. Systematic experimental ADF-STEM images of the edge-character dislocations reveal a number of characteristic contrast features that are shown to depend on both the angular detection range and specific position of the dislocation in the sample. A theoretical model based on electron channelling and Bloch-wave scattering theories, supported by numerical simulations based on Grillo's strain-channelling equation, is proposed to elucidate the physical origin of such complex contrast phenomena.
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Affiliation(s)
- E Oveisi
- Interdisciplinary Centre for Electron Microscopy, École Polytechnique Fédérale de Lausanne (CIME-EPFL), Lausanne, Switzerland; Electron Spectrometry and Microscopy Laboratory, École Polytechnique Fédérale de Lausanne (LSME-EPFL), Lausanne, Switzerland.
| | - M C Spadaro
- Interdisciplinary Centre for Electron Microscopy, École Polytechnique Fédérale de Lausanne (CIME-EPFL), Lausanne, Switzerland
| | - E Rotunno
- Institute of Nanoscience, National Research Council (NANO-CNR), Modena, Italy
| | - V Grillo
- Institute of Nanoscience, National Research Council (NANO-CNR), Modena, Italy; Institute of Materials for Electronics and Magnetism, National Research Council (IMEM-CNR), Parma, Italy
| | - C Hébert
- Interdisciplinary Centre for Electron Microscopy, École Polytechnique Fédérale de Lausanne (CIME-EPFL), Lausanne, Switzerland; Electron Spectrometry and Microscopy Laboratory, École Polytechnique Fédérale de Lausanne (LSME-EPFL), Lausanne, Switzerland.
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5
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Drapeau M, Stelmaszczyk K, Baucom D, Henry M, Hébert C. A process study of long-term treatment: comparing a successful and a less successful outcome. Psychoanalytic Psychotherapy 2019. [DOI: 10.1080/02668734.2018.1558414] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- M. Drapeau
- Department of Educational & Counselling Psychology, McGill University, Montreal, Canada
- Department of Psychiatry, McGill University, Montreal, Canada
| | - K. Stelmaszczyk
- Department of Educational & Counselling Psychology, McGill University, Montreal, Canada
| | - D. Baucom
- Department of Psychology, University of North Carolina, Chapel Hill, NC, USA
| | - M. Henry
- Department of Oncology, McGill University, Montreal, Canada
| | - C. Hébert
- Department of Educational & Counselling Psychology, McGill University, Montreal, Canada
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6
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Hasanzadeh S, Schäublin R, Décamps B, Rousson V, Autissier E, Barthe MF, Hébert C. Three-dimensional scanning transmission electron microscopy of dislocation loops in tungsten. Micron 2018; 113:24-33. [PMID: 29945119 DOI: 10.1016/j.micron.2018.05.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 05/23/2018] [Accepted: 05/23/2018] [Indexed: 10/16/2022]
Abstract
Scanning transmission electron microscopy (STEM) imaging using diffraction contrast is a powerful technique to assess crystal defects. In this work it is used to assess the spatial distribution of radiation induced defect in tungsten. In effect, its irradiation leads to the formation of nanometric dislocation loops that under certain conditions may form intriguing 3-D rafts. In this study, we have irradiated thin tungsten samples in situ in a TEM with 1.2 MeV W ions to 0.017 dpa at room temperature (RT) and at 700 °C. Besides the Burgers vector analysis, the number density and size of the dislocation loops with their spatial arrangement were quantitatively characterized by stereo imaging in STEM mode. Most of the loops have a Burgers vector ½ a0 〈111〉, with some a0 〈100〉 at room temperature. Loops are located mainly in the simulated damage profile but there is also a significant portion in deeper regions of the sample, indicating that loops in W diffuse easily, even at RT. At 700 °C, loops form elongated rafts that contain dislocation segments having a Burgers vector ½ a0 〈111〉. The rafts are narrow and reside on {111} planes; they are elongated along 〈110〉 directions, which correspond, when combined to the rafts' Burgers vector, to the lines of edge dislocations. Compared to conventional TEM, 3-D analysis in STEM appears thus as a powerful technique for quantitative analyses of defects in tungsten, as it allows reducing the background diffraction contrast and reaching thicker areas of the electron transparent foil, here 0.5 μm of tungsten at 200 kV.
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Affiliation(s)
- S Hasanzadeh
- Laboratoire de Spectroscopie et Microscopie Electronique, Institut de Physique, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland
| | - R Schäublin
- Scientific Center for Optical and Electron Microscopy, ETH Zürich, CH-8093 Zurich, Switzerland
| | - B Décamps
- Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), CNRS-IN2P3-Univ. Paris-Sud 11, UMR 8609, Bât. 108, 91405 Orsay, France
| | - V Rousson
- Division de Biostatistique et Méthodes Quantitatives, IUMSP, CHUV, University of Lausanne, CH-1010 Lausanne, Switzerland
| | - E Autissier
- CNRS, UPR3079 CEMHTI, 3A rue de la Férollerie, 45071 Orléans cedex 2, France
| | - M F Barthe
- CNRS, UPR3079 CEMHTI, 3A rue de la Férollerie, 45071 Orléans cedex 2, France
| | - C Hébert
- Laboratoire de Spectroscopie et Microscopie Electronique, Institut de Physique, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland.
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7
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Nabiei F, Badro J, Dennenwaldt T, Oveisi E, Cantoni M, Hébert C, El Goresy A, Barrat JA, Gillet P. A large planetary body inferred from diamond inclusions in a ureilite meteorite. Nat Commun 2018; 9:1327. [PMID: 29666368 PMCID: PMC5904174 DOI: 10.1038/s41467-018-03808-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 03/14/2018] [Indexed: 11/12/2022] Open
Abstract
Planetary formation models show that terrestrial planets are formed by the accretion of tens of Moon- to Mars-sized planetary embryos through energetic giant impacts. However, relics of these large proto-planets are yet to be found. Ureilites are one of the main families of achondritic meteorites and their parent body is believed to have been catastrophically disrupted by an impact during the first 10 million years of the solar system. Here we studied a section of the Almahata Sitta ureilite using transmission electron microscopy, where large diamonds were formed at high pressure inside the parent body. We discovered chromite, phosphate, and (Fe,Ni)-sulfide inclusions embedded in diamond. The composition and morphology of the inclusions can only be explained if the formation pressure was higher than 20 GPa. Such pressures suggest that the ureilite parent body was a Mercury- to Mars-sized planetary embryo. Ureilites are a type of meteorite that are believed to be derived from a parent body that was impacted in the early solar system. Here, the authors analyse inclusions within diamonds from a ureilite meteorite and find that they must have formed at above 20 GPa suggesting the parent body was Mercury- to Mars-sized.
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Affiliation(s)
- Farhang Nabiei
- Earth and Planetary Science Laboratory (EPSL), Institute of Physics, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland. .,Interdisciplinary Center for Electron Microscopy (CIME), Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
| | - James Badro
- Earth and Planetary Science Laboratory (EPSL), Institute of Physics, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.,Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Paris, France
| | - Teresa Dennenwaldt
- Interdisciplinary Center for Electron Microscopy (CIME), Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.,Electron Spectrometry and Microscopy Laboratory (LSME), Institute of Physics, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Emad Oveisi
- Interdisciplinary Center for Electron Microscopy (CIME), Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Marco Cantoni
- Interdisciplinary Center for Electron Microscopy (CIME), Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Cécile Hébert
- Interdisciplinary Center for Electron Microscopy (CIME), Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.,Electron Spectrometry and Microscopy Laboratory (LSME), Institute of Physics, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Ahmed El Goresy
- Bayerisches Geoinstitut, Universität Bayreuth, Bayreuth, Germany
| | - Jean-Alix Barrat
- Institut Universitaire Européen de la Mer, Université de Bretagne Occidentale, Plouzané, France
| | - Philippe Gillet
- Earth and Planetary Science Laboratory (EPSL), Institute of Physics, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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8
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Oveisi E, Letouzey A, De Zanet S, Lucas G, Cantoni M, Fua P, Hébert C. Stereo-vision three-dimensional reconstruction of curvilinear structures imaged with a TEM. Ultramicroscopy 2017; 184:116-124. [PMID: 28888106 DOI: 10.1016/j.ultramic.2017.08.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Revised: 07/01/2017] [Accepted: 08/20/2017] [Indexed: 11/28/2022]
Abstract
Deriving accurate three-dimensional (3-D) structural information of materials at the nanometre level is often crucial for understanding their properties. Tomography in transmission electron microscopy (TEM) is a powerful technique that provides such information. It is however demanding and sometimes inapplicable, as it requires the acquisition of multiple images within a large tilt arc and hence prolonged exposure to electrons. In some cases, prior knowledge about the structure can tremendously simplify the 3-D reconstruction if incorporated adequately. Here, a novel algorithm is presented that is able to produce a full 3-D reconstruction of curvilinear structures from stereo pair of TEM images acquired within a small tilt range that spans from only a few to tens of degrees. Reliability of the algorithm is demonstrated through reconstruction of a model 3-D object from its simulated projections, and is compared with that of conventional tomography. This method is experimentally demonstrated for the 3-D visualization of dislocation arrangements in a deformed metallic micro-pillar.
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Affiliation(s)
- Emad Oveisi
- Interdisciplinary Centre for Electron Microscopy, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland; Electron Spectrometry and Microscopy Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland.
| | - Antoine Letouzey
- Electron Spectrometry and Microscopy Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland; Computer Vision Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland
| | - Sandro De Zanet
- Electron Spectrometry and Microscopy Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland; Computer Vision Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland
| | - Guillaume Lucas
- Interdisciplinary Centre for Electron Microscopy, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland; Electron Spectrometry and Microscopy Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland
| | - Marco Cantoni
- Interdisciplinary Centre for Electron Microscopy, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland
| | - Pascal Fua
- Computer Vision Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland
| | - Cécile Hébert
- Interdisciplinary Centre for Electron Microscopy, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland; Electron Spectrometry and Microscopy Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland.
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9
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Oveisi E, Letouzey A, Alexander DTL, Jeangros Q, Schäublin R, Lucas G, Fua P, Hébert C. Tilt-less 3-D electron imaging and reconstruction of complex curvilinear structures. Sci Rep 2017; 7:10630. [PMID: 28878280 PMCID: PMC5587565 DOI: 10.1038/s41598-017-07537-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 06/29/2017] [Indexed: 11/13/2022] Open
Abstract
The ability to obtain three-dimensional (3-D) information about morphologies of nanostructures elucidates many interesting properties of materials in both physical and biological sciences. Here we demonstrate a novel method in scanning transmission electron microscopy (STEM) that gives a fast and reliable assessment of the 3-D configuration of curvilinear nanostructures, all without needing to tilt the sample through an arc. Using one-dimensional crystalline defects known as dislocations as a prototypical example of a complex curvilinear object, we demonstrate their 3-D reconstruction two orders of magnitude faster than by standard tilt-arc TEM tomographic techniques, from data recorded by selecting different ray paths of the convergent STEM probe. Due to its speed and immunity to problems associated with a tilt arc, the tilt-less 3-D imaging offers important advantages for investigations of radiation-sensitive, polycrystalline, or magnetic materials. Further, by using a segmented detector, the total electron dose is reduced to a single STEM raster scan acquisition; our tilt-less approach will therefore open new avenues for real-time 3-D electron imaging of dynamic processes.
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Affiliation(s)
- Emad Oveisi
- Interdisciplinary Centre for Electron Microscopy, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland. .,Electron Spectrometry and Microscopy Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland.
| | - Antoine Letouzey
- Electron Spectrometry and Microscopy Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland.,Computer Vision Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Duncan T L Alexander
- Interdisciplinary Centre for Electron Microscopy, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Quentin Jeangros
- Interdisciplinary Centre for Electron Microscopy, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Robin Schäublin
- Scientific Centre for Optical and Electron Microscopy, Swiss Federal Institute of Technology in Zurich (ETHZ), CH-8093, Zurich, Switzerland
| | - Guillaume Lucas
- Electron Spectrometry and Microscopy Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Pascal Fua
- Computer Vision Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Cécile Hébert
- Interdisciplinary Centre for Electron Microscopy, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland. .,Electron Spectrometry and Microscopy Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland.
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10
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Lorenzo F, Aebersold AB, Morales-Masis M, Ledinský M, Escrig S, Vetushka A, Alexander DTL, Hessler-Wyser A, Fejfar A, Hébert C, Nicolay S, Ballif C. Direct Imaging of Dopant Distribution in Polycrystalline ZnO Films. ACS Appl Mater Interfaces 2017; 9:7241-7248. [PMID: 28151638 DOI: 10.1021/acsami.6b14350] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Two fundamental requirements of transparent conductive oxides are high conductivity and low optical absorptance, properties strongly dependent on the free-carrier concentration of the film. The free-carrier concentration is usually tuned by the addition of dopant atoms; which are commonly assumed to be uniformly distributed in the films or partially segregated at grain boundaries. Here, the combination of secondary ion mass spectroscopy at the nanometric scale (NanoSIMS) and Kelvin probe force microscopy (KPFM) allows direct imaging of boron-dopant distribution in polycrystalline zinc oxide (ZnO) films. This work demonstrates that the boron atoms have a bimodal spatial distribution within each grain of the ZnO films. NanoSIMS analysis shows that boron atoms are preferentially incorporated into one of the two sides of each ZnO grain. KPFM measurements confirm that boron atoms are electrically active, locally increasing the free-carrier concentration in the film. The proposed cause of this nonuniform dopant distribution is the different sticking coefficient of Zn adatoms on the two distinct surface terminations of the ZnO grains. The higher sticking coefficient of Zn on the c+ surface restricts the boron incorporation on this side of the grains, resulting in preferential boron incorporation on the c- side and causing the bimodal distribution.
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Affiliation(s)
- Fanni Lorenzo
- Ecole Polytechnique Fédérale de Lausanne (EPFL) , Institute of Microengineering, Photovoltaics and Thin-Film Electronics Laboratory, Rue de la Maladière 71B, CH-2000 Neuchâtel, Switzerland
| | - A Brian Aebersold
- Ecole Polytechnique Fédérale de Lausanne (EPFL) , Interdisciplinary Centre for Electron Microscopy (CIME), Station 12, CH-1015 Lausanne, Switzerland
| | - Monica Morales-Masis
- Ecole Polytechnique Fédérale de Lausanne (EPFL) , Institute of Microengineering, Photovoltaics and Thin-Film Electronics Laboratory, Rue de la Maladière 71B, CH-2000 Neuchâtel, Switzerland
| | - Martin Ledinský
- Laboratory of Nanostructures and Nanomaterials, Institute of Physics ASCR , Cukrovarnická 10, 162 00 Prague 6, Czech Republic
| | - Stéphane Escrig
- Ecole Polytechnique Fédérale de Lausanne (EPFL) , Laboratory for Biological Geochemistry, Station 2, CH-1015 Lausanne, Switzerland
| | - Aliaksei Vetushka
- Laboratory of Nanostructures and Nanomaterials, Institute of Physics ASCR , Cukrovarnická 10, 162 00 Prague 6, Czech Republic
| | - Duncan T L Alexander
- Ecole Polytechnique Fédérale de Lausanne (EPFL) , Interdisciplinary Centre for Electron Microscopy (CIME), Station 12, CH-1015 Lausanne, Switzerland
| | - Aïcha Hessler-Wyser
- Ecole Polytechnique Fédérale de Lausanne (EPFL) , Institute of Microengineering, Photovoltaics and Thin-Film Electronics Laboratory, Rue de la Maladière 71B, CH-2000 Neuchâtel, Switzerland
| | - Antonín Fejfar
- Laboratory of Nanostructures and Nanomaterials, Institute of Physics ASCR , Cukrovarnická 10, 162 00 Prague 6, Czech Republic
| | - Cécile Hébert
- Ecole Polytechnique Fédérale de Lausanne (EPFL) , Interdisciplinary Centre for Electron Microscopy (CIME), Station 12, CH-1015 Lausanne, Switzerland
| | - Sylvain Nicolay
- Centre Suisse d'Electronique et Microtechnique , PV-Center, rue Jacques-Droz 1, CH-2002 Neuchâtel, Switzerland
| | - Christophe Ballif
- Ecole Polytechnique Fédérale de Lausanne (EPFL) , Institute of Microengineering, Photovoltaics and Thin-Film Electronics Laboratory, Rue de la Maladière 71B, CH-2000 Neuchâtel, Switzerland
- Centre Suisse d'Electronique et Microtechnique , PV-Center, rue Jacques-Droz 1, CH-2002 Neuchâtel, Switzerland
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11
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Falk A, Hébert C, Paquet M, Tran A, Peyrade F, Saada E, Reure J, Dassonville O, Poissonnet G, Bozec A, Thariat J, Leysalle A, Chand M, Benezery K. EP-1084: Elderly patients concomitant radiotherapy + cetuximab in locally advanced head and neck cancer. Radiother Oncol 2016. [DOI: 10.1016/s0167-8140(16)32334-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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12
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Demurtas D, Guichard P, Martiel I, Mezzenga R, Hébert C, Sagalowicz L. Direct visualization of dispersed lipid bicontinuous cubic phases by cryo-electron tomography. Nat Commun 2015; 6:8915. [PMID: 26573367 DOI: 10.1038/ncomms9915] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 10/16/2015] [Indexed: 02/08/2023] Open
Abstract
Bulk and dispersed cubic liquid crystalline phases (cubosomes), present in the body and in living cell membranes, are believed to play an essential role in biological phenomena. Moreover, their biocompatibility is attractive for nutrient or drug delivery system applications. Here the three-dimensional organization of dispersed cubic lipid self-assembled phases is fully revealed by cryo-electron tomography and compared with simulated structures. It is demonstrated that the interior is constituted of a perfect bicontinuous cubic phase, while the outside shows interlamellar attachments, which represent a transition state between the liquid crystalline interior phase and the outside vesicular structure. Therefore, compositional gradients within cubosomes are inferred, with a lipid bilayer separating at least one water channel set from the external aqueous phase. This is crucial to understand and enhance controlled release of target molecules and calls for a revision of postulated transport mechanisms from cubosomes to the aqueous phase.
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Affiliation(s)
- Davide Demurtas
- Interdisciplinary Centre for Electron Microscopy, Swiss Federal Institute of Technology (EPFL), Lausanne 1015, Switzerland
| | - Paul Guichard
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne 1015, Switzerland
| | - Isabelle Martiel
- Department of Health Science and Technology, ETH Zurich, Zurich 8092, Switzerland
| | - Raffaele Mezzenga
- Department of Health Science and Technology, ETH Zurich, Zurich 8092, Switzerland
| | - Cécile Hébert
- Interdisciplinary Centre for Electron Microscopy, Swiss Federal Institute of Technology (EPFL), Lausanne 1015, Switzerland
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13
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Frémond ML, Pérot P, Muth E, Cros G, Dumarest M, Mahlaoui N, Seilhean D, Desguerre I, Hébert C, Corre-Catelin N, Neven B, Lecuit M, Blanche S, Picard C, Eloit M. Next-Generation Sequencing for Diagnosis and Tailored Therapy: A Case Report of Astrovirus-Associated Progressive Encephalitis. J Pediatric Infect Dis Soc 2015; 4:e53-7. [PMID: 26407445 DOI: 10.1093/jpids/piv040] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 06/09/2015] [Indexed: 01/26/2023]
Abstract
A boy with X-linked agammaglobulinemia experienced progressive global motor decline, cerebellar syndrome, and epilepsy. All standard polymerase chain reactions for neurotropic viruses were negative on cerebrospinal fluid and brain biopsy. Next-generation sequencing allowed fast identification of a new astrovirus strain (HAstV-VA1/HMO-C-PA), which led to tailor the patient's treatment, with encouraging clinical monitoring over 1 year.
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Affiliation(s)
- M-L Frémond
- Unité d'Immuno-Hématologie et Rhumatologie Pédiatrique, Hôpital Universitaire Necker-Enfants Malades, Assistance Publique-Hôpitaux de Paris, France Université Paris Descartes, Sorbonne Paris Cité, Institut Imagine, France
| | - P Pérot
- Institut Pasteur, Biology of Infection Unit, Institut National de la Santé et de la Recherche Médicale (INSERM) U1117, Pathogen Discovery Laboratory, Paris, France
| | - E Muth
- PathoQuest, Paris, France
| | - G Cros
- Unité d'Immuno-Hématologie et Rhumatologie Pédiatrique, Hôpital Universitaire Necker-Enfants Malades, Assistance Publique-Hôpitaux de Paris, France Université Paris Descartes, Sorbonne Paris Cité, Institut Imagine, France
| | - M Dumarest
- Institut Pasteur, Biology of Infection Unit, Institut National de la Santé et de la Recherche Médicale (INSERM) U1117, Pathogen Discovery Laboratory, Paris, France
| | - N Mahlaoui
- Unité d'Immuno-Hématologie et Rhumatologie Pédiatrique, Hôpital Universitaire Necker-Enfants Malades, Assistance Publique-Hôpitaux de Paris, France Université Paris Descartes, Sorbonne Paris Cité, Institut Imagine, France Laboratoire de Génétique Humaine des Maladies Infectieuses, Branche Necker, INSERM U1163, Paris, France Centre de Référence Déficits Immunitaires Héréditaires, Hôpital Universitaire Necker-Enfants Malades, Assistance Publique-Hôpitaux de Paris, France
| | - D Seilhean
- Département de Neuropathologie, Hôpital Universitaire Pitié-Salpétrière, Université Pierre et Marie Curie, Sorbonne Universités, Paris, France
| | - I Desguerre
- Université Paris Descartes, Unité de Neuropédiatrie, Hôpital Universitaire Necker-Enfants Malades, Paris, France
| | | | - N Corre-Catelin
- Investigation Clinique et Accès aux Ressources Biologiques, Institut Pasteur, Paris, France
| | - B Neven
- Unité d'Immuno-Hématologie et Rhumatologie Pédiatrique, Hôpital Universitaire Necker-Enfants Malades, Assistance Publique-Hôpitaux de Paris, France Université Paris Descartes, Sorbonne Paris Cité, Institut Imagine, France
| | - M Lecuit
- Unité d'Immuno-Hématologie et Rhumatologie Pédiatrique, Hôpital Universitaire Necker-Enfants Malades, Assistance Publique-Hôpitaux de Paris, France Paris Descartes University, Sorbonne Paris Cité, Division of Infectious Diseases and Tropical Medicine, Necker-Enfants Malades University Hospital, Institut Imagine, France Institut Pasteur, Biology of Infection Unit, INSERM U1117, Paris, France
| | - S Blanche
- Unité d'Immuno-Hématologie et Rhumatologie Pédiatrique, Hôpital Universitaire Necker-Enfants Malades, Assistance Publique-Hôpitaux de Paris, France Université Paris Descartes, Sorbonne Paris Cité, Institut Imagine, France
| | - C Picard
- Unité d'Immuno-Hématologie et Rhumatologie Pédiatrique, Hôpital Universitaire Necker-Enfants Malades, Assistance Publique-Hôpitaux de Paris, France Centre de Référence Déficits Immunitaires Héréditaires, Hôpital Universitaire Necker-Enfants Malades, Assistance Publique-Hôpitaux de Paris, France
| | - M Eloit
- Institut Pasteur, Biology of Infection Unit, Institut National de la Santé et de la Recherche Médicale (INSERM) U1117, Pathogen Discovery Laboratory, Paris, France PathoQuest, Paris, France
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14
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Alix K, David ML, Lucas G, Alexander DTL, Pailloux F, Hébert C, Pizzagalli L. Gentle quantitative measurement of helium density in nanobubbles in silicon by spectrum imaging. Micron 2015; 77:57-65. [PMID: 26093479 DOI: 10.1016/j.micron.2015.05.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 05/19/2015] [Accepted: 05/19/2015] [Indexed: 11/19/2022]
Abstract
We propose an original method for the determination of the physical properties of nanometer sized helium bubbles using spectrum imaging in an energy-filtered transmission electron microscope. Helium bubbles synthesized by high fluence implantation and thermal annealing in silicon are investigated. The acquisition parameters are determined to optimize both signal/noise ratio and time. The limitations to the extent of observable areas on a typical sample are explained. The necessary data correction and helium K-edge position measurement procedures are detailed and the accuracy of the method is discussed. Finally helium density maps are obtained and discussed.
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Affiliation(s)
- Kévin Alix
- Institut Pprime, UPR3346 CNRS-Université de Poitiers, 86962 Futuroscope-Chasseneuil, France
| | - Marie-Laure David
- Institut Pprime, UPR3346 CNRS-Université de Poitiers, 86962 Futuroscope-Chasseneuil, France.
| | | | | | - Frédéric Pailloux
- Institut Pprime, UPR3346 CNRS-Université de Poitiers, 86962 Futuroscope-Chasseneuil, France
| | - Cécile Hébert
- CIME, EPFL-SB-CIME-GE, CH-1015 Lausanne, Switzerland
| | - Laurent Pizzagalli
- Institut Pprime, UPR3346 CNRS-Université de Poitiers, 86962 Futuroscope-Chasseneuil, France
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15
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Burdet P, Hébert C, Cantoni M. Enhanced quantification for 3D energy dispersive spectrometry: going beyond the limitation of large volume of X-ray emission. Microsc Microanal 2014; 20:1544-1555. [PMID: 24960631 DOI: 10.1017/s1431927614001688] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
This paper presents a method developed to quantify three-dimensional energy dispersive spectrometry (3D EDS) data with voxel size smaller than the volume from which X-rays are emitted. The influence of the neighboring voxels is corrected by applying recursively a complex quantification, improving thereby the accuracy of the quantification of critically small features. The enhanced quantification method is applied to simulated and measured data. A systematic improvement is obtained compared with classical quantification, proving the concept and the prospect of this method.
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Affiliation(s)
- Pierre Burdet
- 1Department of Materials Science and Metallurgy,University of Cambridge,Charles Babbage Road 27,Cambridge CB3 0FS,Cambridgeshire,UK
| | - Cécile Hébert
- 2Centre Interdisciplinaire de Microscopie Electronique,Ecole Polytechnique Fédérale de Lausanne (EPFL),Station 12,Lausanne 1015,Switzerland
| | - Marco Cantoni
- 2Centre Interdisciplinaire de Microscopie Electronique,Ecole Polytechnique Fédérale de Lausanne (EPFL),Station 12,Lausanne 1015,Switzerland
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16
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Hébert C, Scorsone E, Bendali A, Kiran R, Cottance M, Girard HA, Degardin J, Dubus E, Lissorgues G, Rousseau L, Mailley P, Picaud S, Bergonzo P. Boron doped diamond biotechnology: from sensors to neurointerfaces. Faraday Discuss 2014; 172:47-59. [PMID: 25259508 DOI: 10.1039/c4fd00040d] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Boron doped nanocrystalline diamond is known as a remarkable material for the fabrication of sensors, taking advantage of its biocompatibility, electrochemical properties, and stability. Sensors can be fabricated to directly probe physiological species from biofluids (e.g. blood or urine), as will be presented. In collaboration with electrophysiologists and biologists, the technology was adapted to enable structured diamond devices such as microelectrode arrays (MEAs), i.e. common electrophysiology tools, to probe neuronal activity distributed over large populations of neurons or embryonic organs. Specific MEAs can also be used to build neural prostheses or implants to compensate function losses due to lesions or degeneration of parts of the central nervous system, such as retinal implants, which exhibit real promise as biocompatible neuroprostheses for in vivo neuronal stimulations. New electrode geometries enable high performance electrodes to surpass more conventional materials for such applications.
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Affiliation(s)
- C Hébert
- CEA, LIST, Diamond Sensors Laboratory, F-91191, Gif-sur-Yvette, France.
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17
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Jeangros Q, Hansen TW, Wagner JB, Dunin-Borkowski RE, Hébert C, Van herle J, Hessler-Wyser A. Measurements of local chemistry and structure in Ni(O)–YSZ composites during reduction using energy-filtered environmental TEM. Chem Commun (Camb) 2014; 50:1808-10. [DOI: 10.1039/c3cc46682e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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18
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Perdereau S, Touzot F, Robin L, Hébert C, Monceaux F, Dimitrov G. Sténoses pyloriques récidivantes chez un enfant de 7ans atteint de granulomatose septique chronique. Arch Pediatr 2013; 20:1337-9. [DOI: 10.1016/j.arcped.2013.09.029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Accepted: 09/24/2013] [Indexed: 01/15/2023]
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19
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Warren SC, Voïtchovsky K, Dotan H, Leroy CM, Cornuz M, Stellacci F, Hébert C, Rothschild A, Grätzel M. Identifying champion nanostructures for solar water-splitting. Nat Mater 2013; 12:842-9. [PMID: 23832125 DOI: 10.1038/nmat3684] [Citation(s) in RCA: 253] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Accepted: 05/13/2013] [Indexed: 05/20/2023]
Abstract
Charge transport in nanoparticle-based materials underlies many emerging energy-conversion technologies, yet assessing the impact of nanometre-scale structure on charge transport across micrometre-scale distances remains a challenge. Here we develop an approach for correlating the spatial distribution of crystalline and current-carrying domains in entire nanoparticle aggregates. We apply this approach to nanoparticle-based α-Fe₂O₃ electrodes that are of interest in solar-to-hydrogen energy conversion. In correlating structure and charge transport with nanometre resolution across micrometre-scale distances, we have identified the existence of champion nanoparticle aggregates that are most responsible for the high photoelectrochemical activity of the present electrodes. Indeed, when electrodes are fabricated with a high proportion of these champion nanostructures, the electrodes achieve the highest photocurrent of any metal oxide photoanode for photoelectrochemical water-splitting under 100 mW cm(-2) air mass 1.5 global sunlight.
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Affiliation(s)
- Scott C Warren
- 1] Laboratory of Photonics and Interfaces, École Polytechnique Fédérale de Lausanne, Lausanne 1015, Switzerland [2]
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20
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Lucas G, Burdet P, Cantoni M, Hébert C. Multivariate statistical analysis as a tool for the segmentation of 3D spectral data. Micron 2013; 52-53:49-56. [DOI: 10.1016/j.micron.2013.08.005] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 07/26/2013] [Accepted: 08/19/2013] [Indexed: 10/26/2022]
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21
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Laurent S, Ng EP, Thirifays C, Lakiss L, Goupil GM, Mintova S, Burtea C, Oveisi E, Hébert C, de Vries M, Motazacker MM, Rezaee F, Mahmoudi M. Corona protein composition and cytotoxicity evaluation of ultra-small zeolites synthesized from template free precursor suspensions. Toxicol Res (Camb) 2013. [DOI: 10.1039/c3tx50023c] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
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22
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Sikora A, Ftouni H, Richard J, Hébert C, Eon D, Omnès F, Bourgeois O. Highly sensitive thermal conductivity measurements of suspended membranes (SiN and diamond) using a 3ω-Völklein method. Rev Sci Instrum 2012; 83:054902. [PMID: 22667639 DOI: 10.1063/1.4704086] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A suspended system for measuring the thermal properties of membranes is presented. The sensitive thermal measurement is based on the 3ω dynamic method coupled to a Völklein geometry. The device obtained using micro-machining processes allows the measurement of the in-plane thermal conductivity of a membrane with a sensitivity of less than 10 nW/K (+∕-5 × 10(-3) Wm(-1) K(-1) at room temperature) and a very high resolution (ΔK/K = 10(-3)). A transducer (heater/thermometer) centered on the membrane is used to create an oscillation of the heat flux and to measure the temperature oscillation at the third harmonic using a Wheatstone bridge set-up. Power as low as 0.1 nW has been measured at room temperature. The method has been applied to measure thermal properties of low stress silicon nitride and polycrystalline diamond membranes with thickness ranging from 100 nm to 400 nm. The thermal conductivity measured on the polycrystalline diamond membrane support a significant grain size effect on the thermal transport.
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Affiliation(s)
- A Sikora
- Institut NÉEL, CNRS-UJF, 25 avenue des Martyrs, 38042 Grenoble Cedex 9, France
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23
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Cuony P, Alexander DTL, Perez-Wurfl I, Despeisse M, Bugnon G, Boccard M, Söderström T, Hessler-Wyser A, Hébert C, Ballif C. Silicon filaments in silicon oxide for next-generation photovoltaics. Adv Mater 2012; 24:1182-1186. [PMID: 22290779 DOI: 10.1002/adma.201104578] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Revised: 12/20/2011] [Indexed: 05/31/2023]
Abstract
Nanometer wide silicon filaments embedded in an amorphous silicon oxide matrix are grown at low temperatures over a large area. The optical and electrical properties of these mixed-phase nanomaterials can be tuned independently, allowing for advanced light management in high efficiency thin-film silicon solar cells and for band-gap tuning via quantum confinement in third-generation photovoltaics.
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Affiliation(s)
- Peter Cuony
- Photovoltaics and Thin Film Electronics Laboratory, Institute of Microengineering, École Polytechnique Fédérale de Lausanne, Neuchâtel, Switzerland
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24
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Ferrero JM, Largillier R, Michel C, Amiot V, Milano G, Hébert C, Mari V, Courdi A, Figl A, Follana P, Barrière J, Chamorey E. A phase I study of UFT-oral vinorelbine in metastatic breast cancer. Oncology 2011; 81:73-8. [PMID: 21968516 DOI: 10.1159/000330770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Accepted: 06/28/2011] [Indexed: 11/19/2022]
Abstract
BACKGROUND Despite current treatment options, metastatic breast cancer (MBC) remains essentially incurable, requiring research on new drugs or combinations to improve survival and quality of life. PATIENTS AND METHODS This phase I study was designed to define the maximum-tolerated dose (MTD), dose-limiting toxicity (DLT) and recommended dose of all-oral tegafur-uracil (UFT)/folinic acid combined with vinorelbine as chemotherapy for MBC. Starting doses were 40 mg/m(2)/week of oral vinorelbine administered continuously and 250 mg/m(2)/day of UFT plus 90 mg/day of folinic acid from day 1 to day 28, followed by a 1-week rest period. RESULTS Ten patients were included. Eight were evaluable for toxicity and antitumor response. The second dose level was shown to be the MTD. At this dose, 2 out of 5 patients receiving oral vinorelbine at 40 mg/m(2)/week and UFT at 300 mg/m(2)/day developed DLT consisting of grade 3 asthenia and grade 3 nausea despite standard prophylaxis. Other toxicities were grade 1 diarrhea and anemia. There were no treatment-related deaths. CONCLUSIONS The recommended dose for this combination seems to be the first dose level. A stable response was observed for 6 patients (average 33 weeks). This combination appears to be well-tolerated and offers an alternative to intravenous chemotherapy.
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Affiliation(s)
- J M Ferrero
- Department of Medical Oncology, Centre Antoine Lacassagne, Nice, France
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25
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Gao J, Blondeau P, Salice P, Menna E, Bártová B, Hébert C, Leschner J, Kaiser U, Milko M, Ambrosch-Draxl C, Loi MA. Electronic interactions between "pea" and "pod": the case of oligothiophenes encapsulated in carbon nanotubes. Small 2011; 7:1807-1815. [PMID: 21548083 DOI: 10.1002/smll.201100319] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2011] [Revised: 03/16/2011] [Indexed: 05/30/2023]
Abstract
One of the most challenging strategies to achieve tunable nanophotonic devices is to build robust nanohybrids with variable emission in the visible spectral range, while keeping the merits of pristine single-walled carbon nanotubes (SWNTs). This goal is realized by filling SWNTs ("pods") with a series of oligothiophene molecules ("peas"). The physical properties of these peapods are depicted by using aberration-corrected high-resolution transmission electron microscopy, Raman spectroscopy, and other optical methods including steady-state and time-resolved measurements. Visible photoluminescence with quantum yields up to 30% is observed for all the hybrids. The underlying electronic structure is investigated by density functional theory calculations for a series of peapods with different molecular lengths and tube diameters, which demonstrate that van der Waals interactions are the bonding mechanism between the encapsulated molecule and the tube.
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Affiliation(s)
- Jia Gao
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, Groningen, 9747 AG, The Netherlands
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26
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Alkauskas A, Schneider S, Sagmeister S, Ambrosch-Draxl C, Hébert C. Theoretical analysis of the momentum-dependent loss function of bulk Ag. Ultramicroscopy 2010. [DOI: 10.1016/j.ultramic.2009.12.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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27
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Loi MA, Gao J, Cordella F, Blondeau P, Menna E, Bártová B, Hébert C, Lazar S, Botton GA, Milko M, Ambrosch-Draxl C. Encapsulation of conjugated oligomers in single-walled carbon nanotubes: towards nanohybrids for photonic devices. Adv Mater 2010; 22:1635-9. [PMID: 20496395 DOI: 10.1002/adma.200903527] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Affiliation(s)
- Maria Antonietta Loi
- Zernike Institute for Advanced Materials, University of Groningen Nijenborgh 4, Groningen, 9747 AG, The Netherlands.
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28
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Berthiaume R, Bauce E, Hébert C, Brodeur J. Host tree age as a selective pressure leading to local adaptation of a population of a polyphagous Lepidoptera in virgin boreal forest. Bull Entomol Res 2009; 99:493-501. [PMID: 19224661 DOI: 10.1017/s0007485308006536] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We tested the hypothesis that host tree age may act as a selective factor and lead to local adaptation of the hemlock looper (Lambdina fiscellaria), a geometrid Lepidoptera that has a wide geographical distribution and has evolved in different eco-zones characterized by different levels of floristic composition, age structure and fragmentation level. Considering that hemlock looper outbreaks mainly occurred in old forests, we compared the biological performances of two populations. The first population was collected in the northern virgin boreal forest, which is dominated by mature and overmature coniferous stands that have not suffered from human disturbance. The other population was collected in the southern mixed-wood forest, which is more diversified and has been modified by forest harvesting. Larvae were reared under controlled conditions on foliage from three age classes of balsam fir trees: juvenile, mature and overmature. Although we measured significant variations of biological performances between the two populations, no significant effect of the age of the balsam fir trees could be detected for males from both populations or for females from the southern population. However, northern females were strongly affected by the age of balsam fir trees on which they fed, as their pupal weight was 12% higher and their fecundity increased by 27% on overmature trees compared with juvenile ones. These results indicate that under the same selective pressure, females adapt their strategy to maximize their fitness, and thus they appear as the driving force of evolution through the local adaptation concept. Furthermore, the two populations evolved in distinct habitats and their adaptation reflects selective pressures occurring inside their original environment. This is the first report on local adaptation of an herbivore that is mediated by host tree age. Changes in forest age structure may have a considerable impact on insect local adaptation and presumably on their population dynamics.
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Affiliation(s)
- R Berthiaume
- Université Laval, Faculté de Foresterie, Cité Universitaire, Pavillon Abitibi-Price, Québec, QC Canada.
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29
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Barriere J, Thariat J, Chamorey E, Benezery K, Giacchero D, Hébert C, Poissonnet G, Bozec A, Follana P, Peyrade F. 8540 Prospective assessment of cutaneous toxicities and treatment interruptions of the association radiotherapy – cetuximab for head and neck cancer patients. EJC Suppl 2009. [DOI: 10.1016/s1359-6349(09)71631-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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30
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Aydemir U, Borrmann H, Hébert C, Liên NTK, Burkhardt U, Baitinger M, Grin Y. Existence region of type I clathrates in the system Ba-Ni-Ge. Acta Crystallogr A 2009. [DOI: 10.1107/s0108767309094793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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31
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Schattschneider P, Hébert C, Rubino S, Stöger-Pollach M, Rusz J, Novák P. Magnetic circular dichroism in EELS: Towards 10nm resolution. Ultramicroscopy 2008; 108:433-8. [PMID: 17698291 DOI: 10.1016/j.ultramic.2007.07.002] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2007] [Revised: 06/25/2007] [Accepted: 07/03/2007] [Indexed: 11/21/2022]
Abstract
We describe a new experimental setup for the detection of magnetic circular dichroism with fast electrons (EMCD). As compared to earlier findings the signal is an order of magnitude higher, while the probed area could be significantly reduced, allowing a spatial resolution of better than 40 nm. A simplified analysis of the experimental results is based on the decomposition of the mixed dynamic form factor S(q-->,q-->('),E) into a real part related to the scalar product and an imaginary part related to the vector product of the scattering vectors q--> and q-->('). Following the recent detection of chiral electronic transitions in the electron microscope the present experiment is a crucial demonstration of the potential of EMCD for nanoscale investigations.
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32
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Verbeeck J, Hébert C, Rubino S, Novák P, Rusz J, Houdellier F, Gatel C, Schattschneider P. Optimal aperture sizes and positions for EMCD experiments. Ultramicroscopy 2008; 108:865-72. [PMID: 18423875 DOI: 10.1016/j.ultramic.2008.02.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2007] [Revised: 02/21/2008] [Accepted: 02/26/2008] [Indexed: 11/17/2022]
Abstract
The signal-to-noise ratio (SNR) in energy-loss magnetic chiral dichroism (EMCD)--the equivalent of X-ray magnetic circular dichroism (XMCD) in the electron microscope--is optimized with respect to the detector shape, size and position. We show that an important increase in SNR over previous experiments can be obtained when taking much larger detector sizes. We determine the ideal shape of the detector but also show that round apertures are a good compromise if placed in their optimal position. We develop the theory for a simple analytical description of the EMCD experiment and then apply it to dynamical multibeam Bloch wave calculations and to an experimental data set. In all cases it is shown that a significant and welcome improvement of the SNR is possible.
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Affiliation(s)
- J Verbeeck
- EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium.
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33
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Hébert C, Schattschneider P, Rubino S, Novak P, Rusz J, Stöger-Pollach M. Magnetic circular dichroism in electron energy loss spectrometry. Ultramicroscopy 2007; 108:277-84. [PMID: 18060698 DOI: 10.1016/j.ultramic.2007.07.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2007] [Accepted: 07/10/2007] [Indexed: 10/22/2022]
Abstract
The measurement of circular dichroism in the electron microscope is a new, emerging method and, as such, it is subject to constant refinement and improvement. Different ways can be envisaged to record the signal. We present an overview of the key steps in the energy-loss magnetic chiral dichroism (EMCD) experiment as well as a detailed review of the methods used in the intrinsic way where the specimen is used as a beam splitter. Lateral resolution up to 20-30 nm can be achieved, and the use of convergent beam techniques leads to an improved S/N ratio. Dichroic effects are shown for Ni and Co single crystal; as a counterexample, measurements were carried also for a non-magnetic (Ti) sample, where no dichroic effect was found.
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Affiliation(s)
- C Hébert
- CIME-SB, MXC132, EPLF, 1015 Lausanne, Switzerland.
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34
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Zhang J, Su D, Zhang A, Wang D, Schlögl R, Hébert C. Nanocarbon as Robust Catalyst: Mechanistic Insight into Carbon-Mediated Catalysis. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200702466] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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35
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Zhang J, Su D, Zhang A, Wang D, Schlögl R, Hébert C. Nanocarbon as Robust Catalyst: Mechanistic Insight into Carbon-Mediated Catalysis. Angew Chem Int Ed Engl 2007; 46:7319-23. [PMID: 17722129 DOI: 10.1002/anie.200702466] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Jian Zhang
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
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36
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Aldosary F, Tremblay P, Hébert C, Blier P. Atomoxetine, but not paroxetine, blocks norepinephrine reuptake in depressed patientss. CLIN INVEST MED 2007. [DOI: 10.25011/cim.v30i4.2838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Purpose: Paroxetine is a potent serotonin (5-HT) reuptake inhibitor. However, a purported norepinephrine (NE) reuptake blockade action remains to be established. Atomoxetine is a potent NE reuptake inhibitor with the indication of attention deficit hyperactivity disorder (ADHD). The present study was aimed at confirming a NE reuptake inhibitory action with ascending doses of atomoxetine and possibly with paroxetine in depressed patients.
Methods: Patients were randomized to escalating doses of either paroxetine (20 to 50 mg/day), or atomoxetine (25-80 mg/day) in a four to six week period. Inhibition of NE reuptake was assessed using the attenuation of systolic blood pressure (SBP) elevations produced by intravenous injections of tyramine. Tyramine penetrates into peripheral NE terminals via the NE reuptake transporter and releases NE. Then, NE acts on the vascular adrenoceptors, which causes an elevation of SBP. Drugs that block NE reuptake attenuate the pressor effects of tyramine. Two-way ANOVA for repeated measures for doses of tyramine and treatments were used to assess the effects of the different drug regimens on the pressor response to loads of 3–6 mg of tyramine. Sixteen patients with unipolar major depressive disorder were assessed weekly after increasing the dose of paroxetine (9 patients) and atomoxetine (7 patients).
Results: Atomoxetine exerted a robust inhibition of the tyramine response, starting at the dose of 25mg/day in a dose-dependent pattern. Neither the low nor the high doses of paroxetine altered the tyramine pressor response.
Conclusions: These results provide evidence that atomoxetine started significantly inhibiting NE reuptake at subtherapeutic dose for ADHD, whereas paroxetine leaves the activity of the NE transporter unaltered, even at the highest recommended dose for depression.
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37
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Abstract
The Wien2k code is widely used for the calculation of electron energy loss spectra. Low loss spectra can be calculated with the OPTIC package while core loss spectra are calculated with the TELNES program. A new version, TELNES.2, takes into account the effects of relativity for anisotropic materials. In this paper we discuss the effects of different parameters used for the self-consistent calculation of the electron density on the obtained spectra. We give an overview of possibilities for the calculation of complicated systems requiring a super-cell, like defects or disordered systems. We discuss the problem of the core hole and of the calculation of orientation-sensitive spectra and give an overview of results already published.
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Affiliation(s)
- C Hébert
- Institut für Festkörperphysik, Technische Universität Wien, A-1040 Wien, Austria.
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38
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Hébert C, Berthiaume R, Bauce E, Brodeur J. Geographic biotype and host-associated local adaptation in a polyphagous species, Lambdina fiscellaria (Lepidoptera: Geometridae) feeding on balsam fir on Anticosti Island, Canada. Bull Entomol Res 2006; 96:619-27. [PMID: 17201980 DOI: 10.1017/ber2006464] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The debate about mechanisms underlying the evolution of host specialization by herbivorous insects remains open. Natural selection may act locally and lead to different patterns of geographic variation in life history traits of polyphagous herbivores. The hypothesis of genetically-based trade-offs in offspring performance on different hosts has been proposed but this has rarely been demonstrated. Under laboratory conditions, the biological performance of two populations of the hemlock looper Lambdina fiscellaria (Guenée), a highly polyphagous lepidopteran, was compared when reared on three different tree host species: balsam fir, eastern hemlock and sugar maple. One population originated from Anticosti Island, Québec, Canada, where the insect has evolved without having access to two of the three tree species tested, the other being from the mainland where all tree species are present. When reared on balsam fir foliage, which was naturally available to each population, larvae from Anticosti Island underwent four instars compared with five for the mainland population, indicating the existence of geographic biotypes in L. fiscellaria. When reared on the foliage of non-naturally available host trees, larvae from Anticosti Island had a higher incidence of supernumerary instars. This is a unique example where local adaptation to environmental conditions of an insect herbivore is expressed through a differential number of larval instars. Moreover, the Anticosti Island population showed a higher growth related index on the host available to both populations indicating that a fitness trade-off was the evolutionary process underlying the local adaptation of this population on balsam fir.
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Affiliation(s)
- C Hébert
- Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, Sainte-Foy, Québec, Québec, Canada.
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39
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Hébert C, Schöne WD, Su DS. Experimental and theoretical determination of low electron energy loss spectra of Ag and Ru. Ultramicroscopy 2006; 106:1115-9. [PMID: 16934928 DOI: 10.1016/j.ultramic.2006.04.026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2005] [Revised: 12/05/2005] [Accepted: 04/05/2006] [Indexed: 10/24/2022]
Abstract
We show the experimental and calculated q-dependent low energy loss electron energy loss spectrum of Ru and Ag. The spectra were calculated within the time-dependent density-functional theory including local-field effects. For Ag, the momentum transfer was parallel to the (110) direction. For Ru the three main directions (010), (110) and (001) were investigated. The agreement between theory and experiment is very good for Ag and for momentum transfers parallel to the (001) direction of Ru. For momentum transfers parallel to the in-plane directions (110) and (010) the agreement for Ru is not satisfactory, which could be attributed to relativistic effects or to strong localization of the 4d states of Ru.
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Affiliation(s)
- C Hébert
- Institut für Festkörperphysik, Technische Universität Wien, A-1040 Wien, Austria.
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40
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Hébert C, Schattschneider P, Franco H, Jouffrey B. ELNES at magic angle conditions. Ultramicroscopy 2006; 106:1139-43. [PMID: 16934931 DOI: 10.1016/j.ultramic.2006.04.030] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2005] [Revised: 01/12/2006] [Accepted: 04/05/2006] [Indexed: 11/17/2022]
Abstract
If one needs to cancel the effects of the anisotropy of the sample in a EELS experiment in the TEM, a particular couple of values for the collection and convergence angle must be used, called magic angle conditions (MAC). Recent developments in the theory have shown that a full relativistic treatment is mandatory to correctly describe this effect and that the MAC are strongly dependent on the acceleration voltage. We show how the analytical formula can be derived and give the exact analytical solution for the MAC which can then be easily applied to every practical case. We show the consequences of the energy dependence of the magic angle and that the parallelity of the beam will be the limiting factor for high acceleration voltages while for low acceleration voltages the contribution coming from Bragg spots may make it impossible to reach MAC.
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Affiliation(s)
- C Hébert
- Institut für Festkörperphysik, Technische Universität Wien, A-1040 Wien, Austria.
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41
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Eyidi D, Hébert C, Schattschneider P. Short note on parallel illumination in the TEM. Ultramicroscopy 2006; 106:1144-9. [PMID: 16934929 DOI: 10.1016/j.ultramic.2006.04.029] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2005] [Revised: 02/16/2006] [Accepted: 04/05/2006] [Indexed: 10/24/2022]
Abstract
Parallel illumination conditions are required for several experiments in the transmission electron microscope (TEM). The image rotation induced by the helical trajectory of electrons passing through the magnetic field of the TEM lenses inevitably induces an inclination of the beam relative to the optical axis in the object plane--even for an electron which travels parallel to the optical axis in the far field. This angle (shear angle) is vectorially added to the convergence angle; it depends both on the distance to the optical axis and the magnetic field. By using a beam tilt compensation method, the minimum shear angle is found to be of the order of 1 mrad for a field of view of 2 microm in a 200 kV TEM. In practice, "parallel illumination" can only be obtained for fields of view 1 microm.
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Affiliation(s)
- D Eyidi
- University Service Center for Transmission Electron Microscopy, Vienna University of Technology, Wiedner Hauptstrasse 8-10, A-1040 Wien, Austria.
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42
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Schattschneider P, Rubino S, Hébert C, Rusz J, Kunes J, Novák P, Carlino E, Fabrizioli M, Panaccione G, Rossi G. Detection of magnetic circular dichroism using a transmission electron microscope. Nature 2006; 441:486-8. [PMID: 16724061 DOI: 10.1038/nature04778] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2005] [Accepted: 03/29/2006] [Indexed: 11/09/2022]
Abstract
A material is said to exhibit dichroism if its photon absorption spectrum depends on the polarization of the incident radiation. In the case of X-ray magnetic circular dichroism (XMCD), the absorption cross-section of a ferromagnet or a paramagnet in a magnetic field changes when the helicity of a circularly polarized photon is reversed relative to the magnetization direction. Although similarities between X-ray absorption and electron energy-loss spectroscopy in a transmission electron microscope (TEM) have long been recognized, it has been assumed that extending such equivalence to circular dichroism would require the electron beam in the TEM to be spin-polarized. Recently, it was argued on theoretical grounds that this assumption is probably wrong. Here we report the direct experimental detection of magnetic circular dichroism in a TEM. We compare our measurements of electron energy-loss magnetic chiral dichroism (EMCD) with XMCD spectra obtained from the same specimen that, together with theoretical calculations, show that chiral atomic transitions in a specimen are accessible with inelastic electron scattering under particular scattering conditions. This finding could have important consequences for the study of magnetism on the nanometre and subnanometre scales, as EMCD offers the potential for such spatial resolution down to the nanometre scale while providing depth information--in contrast to X-ray methods, which are mainly surface-sensitive.
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Affiliation(s)
- P Schattschneider
- Service Centre for Transmission Electron Microscopy, Wiedner Hauptstrasse 8-10/052, and Institut für Festkörperphysik, Wiedner Hauptstrasse 8-10/138, Technische Universität Wien, A-1040 Wien, Austria.
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43
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Abstract
We resolve the long-standing mysterious discrepancy between the experimental magic angle in EELS--approximately 2theta(E)--and the quantum mechanical prediction of approximately 4theta(E). A relativistic approach surpassing the usually applied kinematic correction yields a magic angle close to the experimental value. The reason is that the relativistic correction of the inelastic scattering cross section in anisotropic systems is significantly higher than in isotropic ones.
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Affiliation(s)
- B Jouffrey
- LMSS-Mat, CNRS-URA 850, Ecole Centrale Paris, Gde Voie des Vignes, F-92295 Châtenay-Malabry, France
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44
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Hébert C, Jouffrey B, Schattschneider P. Comment on “Experimental and theoretical evidence for the magic angle in transmission electron energy loss spectroscopy” by H. Daniels, A. Brown, A. Scott, T. Nichells, B. Rand and R. Brydson. Ultramicroscopy 2004; 101:271-3. [PMID: 15450673 DOI: 10.1016/j.ultramic.2004.07.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2003] [Revised: 06/14/2004] [Accepted: 07/05/2004] [Indexed: 11/22/2022]
Affiliation(s)
- C Hébert
- Institut für Festkörperphysik, Technische Universität Wien, Wiedner Haupstrasse 8-10, A-1040 Wien, Austria.
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45
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Lazar S, Hébert C, Zandbergen HW. Investigation of hexagonal and cubic GaN by high-resolution electron energy-loss spectroscopy and density functional theory. Ultramicroscopy 2004; 98:249-57. [PMID: 15046805 DOI: 10.1016/j.ultramic.2003.08.018] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2003] [Revised: 06/25/2003] [Indexed: 11/29/2022]
Abstract
High-resolution electron energy-loss spectroscopy in a transmission electron microscope is a very powerful method for the study of electronic structure of materials. The fine structure of Ga L(2,3) and N ionization edges in c-GaN and h-GaN was studied using a TEM equipped with a monochromator and high-resolution energy spectrometer. The experimental results were compared with the results of calculation based on the density functional theory using the Wien2k code and show that the best fit is achieved when the core hole effect is taken into account. The effect of the core hole value and the supercell size on the energy-loss near-edge structure have been investigated. A different behaviour was found for c-GaN and h-GaN: better agreement is obtained for a 0.5 core hole for h-GaN and for a full core hole for c-GaN. The anisotropic behaviour of the experimental spectra and calculated spectra for h-GaN have been studied and the "magic" angle was determined.
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Affiliation(s)
- S Lazar
- National Centre for HREM, Department of Nanoscience, Delft University of Technology, Rotterdamseweg 137, Delft 2628 AL, The Netherlands.
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46
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Abstract
Building upon the similarities between inelastic electron scattering and X-ray absorption we show that dichroism can be observed in electron energy loss spectrometry (EELS) in the transmission electron microscope (TEM). Natural or magnetic linear dichroism can be studied in electron scattering experiment with definite wave vector transfer in the interaction.The detection of circular dichroism in the TEM relies on interferometric EELS in a particular scattering geometry that allows extraction of the mixed dynamic form factor from energy loss spectra. Similarities between dichroic signals in energy loss near edge structures and X-ray absorption near edge structures are discussed, and a new experimental setup for dichroic measurements in the TEM is proposed.
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Affiliation(s)
- C Hébert
- Institut für Festkörperphysik, Technische Universität Wien, A-1040 Wien, Austria.
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47
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Abstract
The density functional theory (DFT) is a recognised method for the calculation of electronic properties of materials. As such it can also be used for the calculation of energy loss near edge structures. Some care has to be taken since the DFT is intended for ground state calculation. The effect of the core hole left by the excited electron is different in an insulator and in a metal and can be observed in both cases. For an insulator (MgO, Si), a supercell calculation is needed while in the case of copper, extremely good agreement with experiment can be obtained with a partial core hole calculation. In the particular case of the WIEN code (APW method) we show that calculation of low lying edges (Si L at 99eV) where the initial state is not strongly localised can only be done within the dipole approximation and with some care. Random alloys (CuNi) have been calculated previously using a supercell; we show that a particular version of the virtual crystal approximation gives promising results.
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Affiliation(s)
- C Hébert
- Institut für Festkörper Physik, Technische Universität Wien, A-1040 Wien, Austria.
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48
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Su DS, Hébert C, Willinger M, Schlögl R. Anisotropy and collection angle dependence of the oxygen K ELNES in V2O5: a band-structure calculation study. Micron 2003; 34:227-33. [PMID: 12895494 DOI: 10.1016/s0968-4328(03)00031-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
We present a theoretical study of the anisotropy and collection angle dependence of the oxygen K ELNES in V2O5. Ab initio band-structure calculations were performed with WIEN97, a program package based on the full potential linearised augmented plane waves (FP-LAPW) method. An analysis of the site and angular momentum projected DOS allowed the identification of differently coordinated oxygens and the separation of the oxygen K-edge into contributions from terminal (vanadyl) oxygens, bridging oxygens and chain oxygens. The major contribution to the anisotropy of the O K-edge ELNES could be assigned to transitions at the vanadyl oxygen. Theoretical calculations predict that the extent of changes in the ELNES would be large enough for detection in collection angle dependent O K-edge measurements. A variation in the fine structure of the O K-edge with decreasing collection angle was confirmed by experiments.
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Affiliation(s)
- D S Su
- Department of Inorganic Chemistry, Fritz Haber Institute of the Max Planck Society, D-14195 Berlin, Germany.
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49
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Su DS, Zandbergen HW, Tiemeijer PC, Kothleitner G, Hävecker M, Hébert C, Knop-Gericke A, Freitag BH, Hofer F, Schlögl R. High resolution EELS using monochromator and high performance spectrometer: comparison of V2O5 ELNES with NEXAFS and band structure calculations. Micron 2003; 34:235-8. [PMID: 12895495 DOI: 10.1016/s0968-4328(03)00033-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Using single crystal V2O5 as a sample, we tested the performance of the new aberration corrected GATAN spectrometer on a monochromatised 200 kV FEG FEI (S)TEM. The obtained V L and O K ELNES were compared with that obtained in a common GATAN GIF and that in the new spectrometer, without monochromatised beam. The performance of the new instrumentation is impressive: recorded with an energy-resolution of 0.22 eV, the V L(3) edge reveals all the features due to the bulk electronic structure, that are also revealed in near-edge X-ray absorption fine structure (NEXAFS) with a much higher energy-resolution (0.08 eV). All features of the ELNES and NEXAFS are in line with a theoretical spectrum derived from band-structure calculations.
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Affiliation(s)
- D S Su
- Department of Inorganic Chemistry, Fritz-Haber-Institute of the Max-Planck-Society, D-14195 Berlin, Germany.
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Abstract
We present a method to separate surface from volume contributions in the fine structure of ionization edges in electron energy loss spectrometry (ELNES). It is based on spectra taken at two positions with different surface-to-volume ratio. Contrary to the similar spatial difference method it uses well defined scaling factors, allowing an estimate of the errors propagated into the result.
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Affiliation(s)
- P Schattschneider
- Institut für Festkörperphysik, Technische Universität Wien, Austria.
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