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Production scientifique
(36) Production(s) de l'année 2024
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A threshold model of plastic waste fragmentation: new insights into the distribution of microplastics in the ocean and its evolution over time
Auteur(s): George M., Nallet Frédéric, Fabre P.
(Article) Publié:
Marine Pollution Bulletin, vol. 199 p.116012 (2024)
Texte intégral en Openaccess :
Ref HAL: hal-04399066_v1
Ref Arxiv: 2307.04162
DOI: 10.1016/j.marpolbul.2023.116012
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé: Plastic pollution in the aquatic environment has been assessed for many years by ocean waste collection expeditions around the globe or by river sampling. While the total amount of plastic produced worldwide is well documented, the amount of plastic found in the ocean, the distribution of particles on its surface and its evolution over time are still the subject of much debate. In this article, we propose a general fragmentation model, postulating the existence of a critical size below which particle fragmentation becomes extremely unlikely. In the frame of this model, an abundance peak appears for sizes around 1mm, in agreement with real environmental data. Using, in addition, a realistic exponential waste feed to the ocean, we discuss the relative impact of fragmentation and feed rates, and the temporal evolution of microplastics (MP) distribution. New conclusions on the temporal trend of MP pollution are drawn.
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Purcell Enhancement of Silicon W Centers in Circular Bragg Grating Cavities
Auteur(s): Lefaucher Baptiste, Jager Jean-Baptiste, Calvo Vincent
(Article) Publié:
Acs Photonics, vol. 11 p.24–32 (2024)
Texte intégral en Openaccess :
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Giant anisotropy and Casimir phenomena: the case of carbon nanotube metasurfaces
Auteur(s): Rodriguez-Lopez Pablo, Le Dai-Nam, Bondarev Igor V, Antezza M., Woods Lilia M
(Article) Publié:
Physical Review B, vol. 109 p.035422 (2024)
Texte intégral en Openaccess :
Ref HAL: hal-04324164_v1
Ref Arxiv: 2311.05001
Ref INSPIRE: 2720608
DOI: 10.1103/PhysRevB.109.035422
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé: The Casimir interaction and torque are related phenomena originating from the exchange of electromagnetic excitations between objects. While the Casimir force exists between any types of objects, the materials or geometrical anisotropy drives the emergence of the Casimir torque. Here both phenomena are studied theoretically between dielectric films with immersed parallel single wall carbon nanotubes in the dilute limit with their chirality and collective electronic and optical response properties taken into account. It is found that the Casimir interaction is dominated by thermal fluctuations at sub-micron separations, while the torque is primarily determined by quantum mechanical effects. This peculiar quantum vs. thermal separation is attributed to the strong influence of reduced dimensionality and inherent anisotropy of the materials. Our study suggests that nanostructured anisotropic materials can serve as novel platforms to uncover new functionalities in ubiquitous Casimir phenomena.
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Band gap engineering of Au doping and Au -N codoping into anatase TiO 2 for enhancing the visible light photocatalytic performance
Auteur(s): Benali Kanoun Mohammed, Ahmed Faheem, Awada Chawki, Jonin C., Brevet Pierre-François
(Article) Publié:
International Journal Of Hydrogen Energy, vol. 51 p.907 (2024)
Ref HAL: hal-04274983_v1
DOI: 10.1016/j.ijhydene.2023.10.244
Exporter : BibTex | endNote
Résumé: We investigate anatase TiO 2 doping with Au to determine the change in the band gap energy and optoelectronic properties using experimental and theoretical analysis. The structural analysis using XRD patterns revealed that the synthesized materials primarily exhibited an anatase phase of TiO 2 , with no impurity peaks observed. However, as the concentration of Au increased, additional diffraction peaks corresponding to Au crystalline phases were detected, indicating successful doping. Furthermore, the crystallite size was found to decrease with increasing Au concentration. We observe that the band gap reduces through substitution of Au into the TiO 2 lattice from 3.09 eV to 2.78 eV, demonstrating the feasibility of bandgap tuning of the TiO 2 system. A redshift for Au doped TiO 2 is observed from absorption spectroscopy and optical absorption intensity using hybrid density functional theory, facilitating visible light absorption, although with potential electron-hole recombination limitations. To enhance a visible light photocatalytic activity for water splitting, we extend our work to explore the impact of N and Au codoping into TiO 2 lattice. It reveals that the combination between N and Au leads to a suitable reduction in the band gap width of pure TiO 2. Interestingly, Au-N codoping may decrease the effect of photogenerated carriers, produce a new optical absorption feature in the visible region, and enhance the photocatalytic performance of TiO 2. This codoping configuration is also a promising photocatalyst for the decomposition of water using visible light without inducing unoccupied states.
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Influence of the Quantum Capacitance on Electrolyte Conductivity through Carbon Nanotubes
Auteur(s): Hennequin-Nespoulous Théo, Manghi Manoel, Noury A., Henn F., Jourdain V., Palmeri J.
(Article) Publié:
Journal Of Physical Chemistry Letters, vol. 15 p.2177–2183 (2024)
Texte intégral en Openaccess :
Ref HAL: hal-04234607_v1
Ref Arxiv: 2307.12071
DOI: 10.1021/acs.jpclett.3c03248
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé: In recent experiments, unprecedentedly large values for the conductivity of electrolytes through carbon nanotubes (CNTs) have been measured, possibly owing to flow slip and a high pore surface charge density whose origin is still unknown. By accounting for the coupling between the {quantum} CNT and the {classical} electrolyte-filled pore capacitances, we study the case where a gate voltage is applied to the CNT. The computed surface charge and conductivity dependence on reservoir salt concentration and gate voltage are intimately connected to the CNT electronic density of states. This approach provides key insight into why metallic CNTs have larger conductivities than semi-conducting ones.
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Hypermultiplet metric and NS5-instantons
Auteur(s): Alexandrov S., Bendriss K.
(Article) Publié:
Jhep, vol. 01 p.140 (2024)
Texte intégral en Openaccess :
Ref HAL: hal-04236880_v1
Ref Arxiv: 2309.14440
Ref INSPIRE: 2703100
DOI: 10.1007/JHEP01(2024)140
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé: The metric on the hypermultiplet moduli space of Calabi-Yau compactifications of type II string theory is known to receive D-brane and NS5-brane instanton corrections. We compute explicit expressions for these corrections in the one-instanton approximation, but to all orders in the string coupling expansion around the instantons. As a consistency check, we prove that in the case of one (universal) hypermultiplet, the resulting metric fits the Przanowski description of self-dual Einstein spaces. We also show that in the small string coupling limit the metric acquires a certain square structure, consistently with expectations from the string amplitudes analysis. This result provides explicit predictions for yet mysterious string amplitudes in the presence of NS5-branes.
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Chromatin structure from high resolution microscopy: scaling laws and microphase separation
Auteur(s): Remini L., Segers Midas, Palmeri J., Walter J.-C., Parmeggiani A., Carlon Enrico
(Article) Publié:
Physical Review E, vol. 109 p.024408 (2024)
Ref HAL: hal-04177307_v3
DOI: 10.1103/PhysRevE.109.024408
Exporter : BibTex | endNote
Résumé: Recent advances in experimental fluorescence microscopy allow high accuracy determination (resolution of 50nm) of the 3D physical location of multiple (up to ~10^2) tagged regions of the chromosome. We investigate publicly available microscopy data for two loci of the human Chr.21 obtained from multiplexed FISH methods for different cell lines and treatments. Inspired by polymer physics models, our analysis centers around distance distributions between different tags, aiming to unravel the chromatin conformational arrangements. We show that for any specific genomic site, there are (at least) two different conformational arrangements of chromatin, implying coexisting distinct topologies which we refer to as phase "alpha" and phase "beta". These two phases show different scaling behaviors: the former is consistent with a crumpled globule while the latter indicates a confined, but more extended conformation, as a looped domain. The identification of these distinct phases sheds light on the coexistence of multiple chromatin topologies and provides insights into the effects of cellular context and/or treatments on chromatin structure.
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