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Kolasiński K, Sellier H, Szafran B. Extraction of the Rashba spin-orbit coupling constant from scanning gate microscopy conductance maps for quantum point contacts. Sci Rep 2017; 7:14935. [PMID: 29097691 PMCID: PMC5668439 DOI: 10.1038/s41598-017-14380-2] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 10/09/2017] [Indexed: 11/09/2022] Open
Abstract
We study the possibility for the extraction of the Rashba spin-orbit coupling constant for a two-dimensional electron gas with the conductance microscopy technique. Due to the interplay between the effective magnetic field due to the Rashba spin-orbit coupling and the external magnetic field applied within the plane of confinement, the electron backscattering induced by a charged tip of an atomic force microscope located above the sample leads to the spin precession and spin mixing of the incident and reflected electron waves between the QPC and the tip-induced 2DEG depletion region. This mixing leads to a characteristic angle-dependent beating pattern visible in the conductance maps. We show that the structure of the Fermi level, bearing signatures of the spin-orbit coupling, can be extracted from the Fourier transform of the interference fringes in the conductance maps as a function of the magnetic field direction. We propose a simple analytical model which can be used to fit the experimental data in order to obtain the spin-orbit coupling constant.
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Affiliation(s)
- K Kolasiński
- AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. Mickiewicza 30, 30-059, Kraków, Poland
| | - H Sellier
- Université Grenoble Alpes, CNRS, Institut Néel, 38000, Grenoble, France
| | - B Szafran
- AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. Mickiewicza 30, 30-059, Kraków, Poland.
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2
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Moles A, Butterworth JA, Sanchez A, Hunter JE, Leslie J, Sellier H, Tiniakos D, Cockell SJ, Mann DA, Oakley F, Perkins ND. A RelA(p65) Thr505 phospho-site mutation reveals an important mechanism regulating NF-κB-dependent liver regeneration and cancer. Oncogene 2016; 35:4623-32. [PMID: 26853469 PMCID: PMC4862573 DOI: 10.1038/onc.2015.526] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 10/08/2015] [Accepted: 11/03/2015] [Indexed: 02/08/2023]
Abstract
Post-translational modifications of nuclear factor (NF)-κB subunits provide a mechanism to differentially regulate their activity in response to the many stimuli that induce this pathway. However, the physiological significance of these modifications is largely unknown, and it remains unclear if these have a critical role in the normal and pathological functions of NF-κB in vivo. Among these, phosphorylation of the RelA(p65) Thr505 residue has been described as an important regulator of NF-κB activity in cell lines, but its physiological significance was not known. Therefore, to learn more about the role of this pathway in vivo, we generated a knockin mouse with a RelA T505A mutation. Unlike RelA knockout mice, the RelA T505A mice develop normally but exhibit aberrant hepatocyte proliferation following liver partial hepatectomy or damage resulting from carbon tetrachloride (CCl4) treatment. Consistent with these effects, RelA T505A mice exhibit earlier onset of cancer in the N-nitrosodiethylamine model of hepatocellular carcinoma. These data reveal a critical pathway controlling NF-κB function in the liver that acts to suppress the tumour-promoting activities of RelA.
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Affiliation(s)
- A Moles
- Institute of Cellular Medicine, Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - J A Butterworth
- Institute for Cell and Molecular Biosciences (ICaMB), Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - A Sanchez
- Institute for Cell and Molecular Biosciences (ICaMB), Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - J E Hunter
- Institute for Cell and Molecular Biosciences (ICaMB), Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - J Leslie
- Institute of Cellular Medicine, Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - H Sellier
- Institute for Cell and Molecular Biosciences (ICaMB), Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - D Tiniakos
- Institute of Cellular Medicine, Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - S J Cockell
- Bioinformatics Support Unit, Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - D A Mann
- Institute of Cellular Medicine, Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - F Oakley
- Institute of Cellular Medicine, Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - N D Perkins
- Institute for Cell and Molecular Biosciences (ICaMB), Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, UK
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3
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Hunter JE, Butterworth JA, Zhao B, Sellier H, Campbell KJ, Thomas HD, Bacon CM, Cockell SJ, Gewurz BE, Perkins ND. The NF-κB subunit c-Rel regulates Bach2 tumour suppressor expression in B-cell lymphoma. Oncogene 2016; 35:3476-84. [PMID: 26522720 PMCID: PMC4853301 DOI: 10.1038/onc.2015.399] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 08/13/2015] [Accepted: 09/04/2015] [Indexed: 12/15/2022]
Abstract
The REL gene, encoding the NF-κB subunit c-Rel, is frequently amplified in B-cell lymphoma and functions as a tumour-promoting transcription factor. Here we report the surprising result that c-rel-/- mice display significantly earlier lymphomagenesis in the c-Myc driven, Eμ-Myc model of B-cell lymphoma. c-Rel loss also led to earlier onset of disease in a separate TCL1-Tg-driven lymphoma model. Tumour reimplantation experiments indicated that this is an effect intrinsic to the Eμ-Myc lymphoma cells but, counterintuitively, c-rel-/- Eμ-Myc lymphoma cells were more sensitive to apoptotic stimuli. To learn more about why loss of c-Rel led to earlier onset of disease, microarray gene expression analysis was performed on B cells from 4-week-old, wild-type and c-rel-/- Eμ-Myc mice. Extensive changes in gene expression were not seen at this age, but among those transcripts significantly downregulated by the loss of c-Rel was the B-cell tumour suppressor BTB and CNC homology 2 (Bach2). Quantitative PCR and western blot analysis confirmed loss of Bach2 in c-Rel mutant Eμ-Myc tumours at both 4 weeks and the terminal stages of disease. Moreover, Bach2 expression was also downregulated in c-rel-/- TCL1-Tg mice and RelA Thr505Ala mutant Eμ-Myc mice. Analysis of wild-type Eμ-Myc mice demonstrated that the population expressing low levels of Bach2 exhibited the earlier onset of lymphoma seen in c-rel-/- mice. Confirming the relevance of these findings to human disease, analysis of chromatin immunoprecipitation sequencing data revealed that Bach2 is a c-Rel and NF-κB target gene in transformed human B cells, whereas treatment of Burkitt's lymphoma cells with inhibitors of the NF-κB/IκB kinase pathway or deletion of c-Rel or RelA resulted in loss of Bach2 expression. These data reveal a surprising tumour suppressor role for c-Rel in lymphoma development explained by regulation of Bach2 expression, underlining the context-dependent complexity of NF-κB signalling in cancer.
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Affiliation(s)
- J E Hunter
- Institute for Cell and Molecular Biosciences (ICaMB), Newcastle University Medical School, Newcastle Upon Tyne, UK
| | - J A Butterworth
- Institute for Cell and Molecular Biosciences (ICaMB), Newcastle University Medical School, Newcastle Upon Tyne, UK
| | - B Zhao
- Brigham and Women's Hospital, Boston, MA, USA
| | - H Sellier
- Institute for Cell and Molecular Biosciences (ICaMB), Newcastle University Medical School, Newcastle Upon Tyne, UK
| | - K J Campbell
- The Beatson Institute for Cancer Research, Glasgow, UK
| | - H D Thomas
- Northern Institute for Cancer Research, Newcastle Upon Tyne, UK
| | - C M Bacon
- Northern Institute for Cancer Research, Newcastle Upon Tyne, UK
| | - S J Cockell
- Bioinformatics Support Unit, Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - B E Gewurz
- Brigham and Women's Hospital, Boston, MA, USA
| | - N D Perkins
- Institute for Cell and Molecular Biosciences (ICaMB), Newcastle University Medical School, Newcastle Upon Tyne, UK
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4
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Brun B, Martins F, Faniel S, Hackens B, Cavanna A, Ulysse C, Ouerghi A, Gennser U, Mailly D, Simon P, Huant S, Bayot V, Sanquer M, Sellier H. Electron Phase Shift at the Zero-Bias Anomaly of Quantum Point Contacts. Phys Rev Lett 2016; 116:136801. [PMID: 27081995 DOI: 10.1103/physrevlett.116.136801] [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] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Indexed: 06/05/2023]
Abstract
The Kondo effect is the many-body screening of a local spin by a cloud of electrons at very low temperature. It has been proposed as an explanation of the zero-bias anomaly in quantum point contacts where interactions drive a spontaneous charge localization. However, the Kondo origin of this anomaly remains under debate, and additional experimental evidence is necessary. Here we report on the first phase-sensitive measurement of the zero-bias anomaly in quantum point contacts using a scanning gate microscope to create an electronic interferometer. We observe an abrupt shift of the interference fringes by half a period in the bias range of the zero-bias anomaly, a behavior which cannot be reproduced by single-particle models. We instead relate it to the phase shift experienced by electrons scattering off a Kondo system. Our experiment therefore provides new evidence of this many-body effect in quantum point contacts.
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Affiliation(s)
- B Brun
- Université Grenoble Alpes, F-38000 Grenoble, France
- CNRS, Institut NEEL, F-38042 Grenoble, France
| | - F Martins
- IMCN/NAPS, Université catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
| | - S Faniel
- IMCN/NAPS, Université catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
| | - B Hackens
- IMCN/NAPS, Université catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
| | - A Cavanna
- CNRS, Laboratoire de Photonique et de Nanostructures, UPR20, F-91460 Marcoussis, France
| | - C Ulysse
- CNRS, Laboratoire de Photonique et de Nanostructures, UPR20, F-91460 Marcoussis, France
| | - A Ouerghi
- CNRS, Laboratoire de Photonique et de Nanostructures, UPR20, F-91460 Marcoussis, France
| | - U Gennser
- CNRS, Laboratoire de Photonique et de Nanostructures, UPR20, F-91460 Marcoussis, France
| | - D Mailly
- CNRS, Laboratoire de Photonique et de Nanostructures, UPR20, F-91460 Marcoussis, France
| | - P Simon
- Laboratoire de Physique des Solides, Université Paris-Sud, F-91405 Orsay, France
| | - S Huant
- Université Grenoble Alpes, F-38000 Grenoble, France
- CNRS, Institut NEEL, F-38042 Grenoble, France
| | - V Bayot
- Université Grenoble Alpes, F-38000 Grenoble, France
- IMCN/NAPS, Université catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
| | - M Sanquer
- Université Grenoble Alpes, F-38000 Grenoble, France
- CEA, INAC-SPSMS, F-38054 Grenoble, France
| | - H Sellier
- Université Grenoble Alpes, F-38000 Grenoble, France
- CNRS, Institut NEEL, F-38042 Grenoble, France
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5
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Lucau-Danila A, Toitot C, Goulas E, Blervacq AS, Hot D, Bahrman N, Sellier H, Lejeune-Hénaut I, Delbreil B. Transcriptome analysis in pea allows to distinguish chilling and acclimation mechanisms. Plant Physiol Biochem 2012; 58:236-44. [PMID: 22858528 DOI: 10.1016/j.plaphy.2012.07.012] [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] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 07/12/2012] [Indexed: 05/04/2023]
Abstract
In order to distinguish chilling and freezing tolerance mechanisms in pea, responses to cold exposure were compared between the freezing tolerant line Champagne and the sensitive line Terese. Global gene expression was considered in the two lines and associated with morphological, histological and biochemical approaches. The chilling tolerance in both lines was related to responses of the CBF, COR and LEA genes belonging to the CBF regulon, with greater earliness of expression in the Champagne genotype. The freezing tolerance, only observed in Champagne, was associated with acclimation processes such as cellular osmotic stabilization, photosynthesis modifications, antioxidants production, modifications in hormone metabolism, cell wall composition and dynamics.
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Affiliation(s)
- A Lucau-Danila
- UMR 1281, Université Lille1-INRA, USTL, Stress Abiotiques et Différenciation des Végétaux cultivés, Bâtiment SN2, F-59650 Villeneuve d'Ascq, France.
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6
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Pala MG, Baltazar S, Liu P, Sellier H, Hackens B, Martins F, Bayot V, Wallart X, Desplanque L, Huant S. Transport inefficiency in branched-out mesoscopic networks: an analog of the Braess paradox. Phys Rev Lett 2012; 108:076802. [PMID: 22401236 DOI: 10.1103/physrevlett.108.076802] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Indexed: 05/31/2023]
Abstract
We present evidence for a counterintuitive behavior of semiconductor mesoscopic networks that is the analog of the Braess paradox encountered in classical networks. A numerical simulation of quantum transport in a two-branch mesoscopic network reveals that adding a third branch can paradoxically induce transport inefficiency that manifests itself in a sizable conductance drop of the network. A scanning-probe experiment using a biased tip to modulate the transmission of one branch in the network reveals the occurrence of this paradox by mapping the conductance variation as a function of the tip voltage and position.
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Affiliation(s)
- M G Pala
- IMEP-LAHC, Grenoble INP, Minatec, BP 257, Grenoble, France.
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7
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Laurent J, Drezet A, Sellier H, Chevrier J, Huant S. Large variation in the boundary-condition slippage for a rarefied gas flowing between two surfaces. Phys Rev Lett 2011; 107:164501. [PMID: 22107390 DOI: 10.1103/physrevlett.107.164501] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Indexed: 05/31/2023]
Abstract
We study the slippage of a gas along mobile rigid walls in the sphere-plane confined geometry and find that it varies considerably with pressure. The classical no-slip boundary condition valid at ambient pressure changes continuously to an almost perfect slip condition in a primary vacuum. Our study emphasizes the key role played by the mean free path of the gas molecules on the interaction between a confined fluid and solid surfaces and further demonstrates that the macroscopic hydrodynamics approach can be used with confidence even in a primary vacuum environment where it is intuitively expected to fail.
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Affiliation(s)
- J Laurent
- Institut Néel, CNRS and Université Joseph Fourier, Grenoble, France
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8
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Laurent J, Mosset A, Arcizet O, Chevrier J, Huant S, Sellier H. "Negative" backaction noise in interferometric detection of a microlever. Phys Rev Lett 2011; 107:050801. [PMID: 21867055 DOI: 10.1103/physrevlett.107.050801] [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] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 05/24/2011] [Indexed: 05/31/2023]
Abstract
Interferometric detection of mirror displacements is intrinsically limited by laser shot noise. In practice, however, it is often limited by thermal noise. Here we report on an experiment performed at the liquid helium temperature to overcome the thermal noise limitation and investigate the effect of classical laser noise on a microlever that forms a Fabry-Perot cavity with an optical fiber. The spectral noise densities show a region of "negative" contribution of the backaction noise close to the resonance frequency. We interpret this noise reduction as a coherent coupling of the microlever to the laser intensity noise. This optomechanical effect could be used to improve the detection sensitivity as discussed in proposals going beyond the standard quantum limit.
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Affiliation(s)
- J Laurent
- Institut Néel, CNRS et Université Joseph Fourier, Grenoble, France
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Pala MG, Baltazar S, Martins F, Hackens B, Sellier H, Ouisse T, Bayot V, Huant S. Scanning gate microscopy of quantum rings: effects of an external magnetic field and of charged defects. Nanotechnology 2009; 20:264021. [PMID: 19509453 DOI: 10.1088/0957-4484/20/26/264021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We study scanning gate microscopy (SGM) in open quantum rings obtained from buried semiconductor InGaAs/InAlAs heterostructures. By performing a theoretical analysis based on the Keldysh-Green function approach we interpret the radial fringes observed in experiments as the effect of randomly distributed charged defects. We associate SGM conductance images with the local density of states (LDOS) of the system. We show that such an association cannot be made with the current density distribution. By varying an external magnetic field we are able to reproduce recursive quasi-classical orbits in LDOS and conductance images, which bear the same periodicity as the Aharonov-Bohm effect.
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Affiliation(s)
- M G Pala
- IMEP-LAHC, Grenoble INP Minatec, BP 257, F-38016 Grenoble, France.
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Martins F, Hackens B, Pala MG, Ouisse T, Sellier H, Wallart X, Bollaert S, Cappy A, Chevrier J, Bayot V, Huant S. Imaging electron wave functions inside open quantum rings. Phys Rev Lett 2007; 99:136807. [PMID: 17930624 DOI: 10.1103/physrevlett.99.136807] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2007] [Indexed: 05/25/2023]
Abstract
Combining scanning gate microscopy (SGM) experiments and simulations, we demonstrate low temperature imaging of the electron probability density |Psi|(2)(x,y) in embedded mesoscopic quantum rings. The tip-induced conductance modulations share the same temperature dependence as the Aharonov-Bohm effect, indicating that they originate from electron wave function interferences. Simulations of both |Psi|(2)(x,y) and SGM conductance maps reproduce the main experimental observations and link fringes in SGM images to |Psi|(2)(x,y).
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Affiliation(s)
- F Martins
- Institut Néel, CNRS and Université Joseph Fourier, BP 166, 38042 Grenoble cedex 9, France
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Sellier H, Lansbergen GP, Caro J, Rogge S, Collaert N, Ferain I, Jurczak M, Biesemans S. Transport spectroscopy of a single dopant in a gated silicon nanowire. Phys Rev Lett 2006; 97:206805. [PMID: 17155705 DOI: 10.1103/physrevlett.97.206805] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2006] [Indexed: 05/12/2023]
Abstract
We report on spectroscopy of a single dopant atom in silicon by resonant tunneling between source and drain of a gated nanowire etched from silicon on insulator. The electronic states of this dopant isolated in the channel appear as resonances in the low temperature conductance at energies below the conduction band edge. We observe the two possible charge states successively occupied by spin-up and spin-down electrons under magnetic field. The first resonance is consistent with the binding energy of the neutral D0 state of an arsenic donor. The second resonance shows a reduced charging energy due to the electrostatic coupling of the charged D- state with electrodes. Excited states and Zeeman splitting under magnetic field present large energies potentially useful to build atomic scale devices.
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Affiliation(s)
- H Sellier
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
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