Ref HAL: hal-02973233_v1
Ref Arxiv: 2009.14769
Ref INSPIRE: 1820612
DOI: 10.1103/PhysRevB.102.195422
Ref. & Cit.: NASA ADS
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Résumé:

We derive the Casimir-Polder force and Casimir torque expressions for an anisotropic molecule close to a conducting plane with a tensorial conductivity. We apply our general expressions to the case of a carbon dioxide CO2 molecule close to a plane with pure Hall conductivity and to graphene. We show that the equilibrium position of this linear molecule is with its main axis perpendicular to the surface. We hence conjecture a possible way to exploit the Casimir torque to mechanically improve the performance of CO2 separation membranes useful for an efficient atmospheric CO2 reduction.

Ref HAL: hal-02965425_v1
DOI: 10.1039/d0py01147a
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Résumé:

The synthesis of a copolymer derived from poly(3-hexylthiophene), one of the monomers bearing an aniline group, is described. Like the homopolymer, this copolymer is able to functionalize carbon nanotubes by π-stacking of the thiophene units onto the hexagonal network of the nanotubes. It can as well be covalently attached onto carbon nanotube walls without the need for an intermediate chemical step. While the dispersion of non-covalent nanohybrids in THF is stable for only a few hours, one of the covalent nanohybrids is stable for weeks, showing the efficiency of the functionalization. The comparison between the spectroscopic characterization of both covalent and non-covalent systems shows that the copolymer organizes differently at the interface with the nanotubes in each case, in agreement with the effectiveness of the addition reaction.

Ref HAL: hal-02965925_v1
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Ref HAL: hal-03043414_v1
DOI: 10.1007/s11214-020-00734-2
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Résumé:

This paper describes the design and performance of the search coil magnetometers (SCM), which are part of the Plasma Wave Investigation (PWI) instrument onboard the BepiColombo/Mio spacecraft (Mercury Magnetospheric Orbiter), which will measure the electric field, plasma waves and radio waves for the first time in Mercury’s plasma environment. The SCM consists of two low-frequency orthogonal search coil sensors (LF-SC) measuring two components of the magnetic field (0.1 Hz – 20 kHz) in the spacecraft spin plane, and a dual-band search coil sensor (DB-SC) picking up the third component along the spin axis at both low-frequencies (LF: 0.1 Hz – 20 kHz) and high-frequencies (HF: 10 kHz – 640 kHz). The DB-SC and the two LF-SC sensors form a tri-axial configuration at the tip of a 4.6-m coilable mast (MAST-SC) extending from the spacecraft body, to minimize artificial magnetic field contamination emitted by the spacecraft electronics. After the successful launch of the spacecraft on 20 October 2018, an initial function check for the SCM was conducted. The nominal function and performance of the sensors and preamplifiers were confirmed, even with the MAST-SC being retracted and stowed in the spacecraft body, resulting in the detection of large interference signals likely from spacecraft electronics. The MAST-SC is scheduled for deployment after the Mercury orbit insertion of Mio in 2025, allowing the SCM to make the first higher frequency measurements of magnetic fluctuations in the Hermean magnetosphere and exosphere, and the local solar wind. These measurements will contribute to the investigation of fundamental problems in the Hermean plasma environment, including turbulence, magnetic reconnection, wave-particle interactions and particle acceleration.

Ref HAL: hal-02961331_v1
DOI: 10.1016/j.nuclphysb.2020.115176
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Résumé:

Free Fermions on vertices of distance-regular graphs are considered. Bipartitions are defined by taking as one part all vertices at a given distance from a reference vertex. The ground state is constructed by filling all states below a certain energy. Borrowing concepts from time and band limiting problems, algebraic Heun operators and Terwilliger algebras, it is shown how to obtain, quite generally, a block tridiagonal matrix that commutes with the entanglement Hamiltonian. The case of the Hadamard graphs is studied in detail within that framework and the existence of the commuting matrix is shown to allow for an analytic diagonalization of the restricted two-point correlation matrix and hence for an explicit determination of the entanglement entropy.

Commentaires: 24 pages, 37 ref.

Ref HAL: hal-02961322_v1
DOI: 10.1063/5.0008372
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Commentaires: 5 pages, 27 ref.

Ref HAL: hal-02961315_v1
DOI: 10.1142/9789811210679_0013
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