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(202) Production(s) de l'année 2020
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Fracture, surface et structure des verres en silicate: aperçu des simulations informatiques atomistiques
Auteur(s): Zhang Z.
(Thèses)
, 2020
Ref HAL: tel-02902601_v1
Exporter : BibTex | endNote
Résumé: La compréhension de la structure et du comportement mécanique des matériaux àl’échelle microscopique est cruciale pour la conception de nouveaux produits aux pro-priétés spécifiques. Cette thèse vise à obtenir des informations microscopiques sur lespropriétés, notamment celles de la fracture, des verres d’oxydes qui sont parmi lesmatériaux les plus utilisés au monde. À cette fin, nous utilisons des techniques desimulation atomistique de pointe pour étudier la silice et des silicates de sodium, c’est-à-dire les compositions représentatives pour de nombreux verres d’oxydes. À l’aide desimulations de dynamique moléculaire à grande échelle, la fracture dynamique des ver-res est étudiée de manière approfondie. Nous montrons que les propriétés mécaniquesdes verres sont considérablement plus sensibles au potentiel d’interaction et au pro-tocole de simulation utilisés qu’à leurs propriétés structurelles. La fracture du verrede silice est due aux ruptures de liaisons en pointe de fissure, tandis que la fracturedes verres riches en Na s’accompagne d’une croissance et d’une coalescence des cavités.Nous montrons également que l’origine microscopique du comportement transitoireprésenté par la rigidité des verres en fonction de leur composition se trouve dans ledéplacements atomiques non affines des atomes constituants. On constate que lessurfaces générées suite à la fracture sont considérablement plus rugueuses que les sur-faces formées par fusion et présentent un comportement en loi logarithmique à l’échellenanométrique (≤ 10 nm). En utilisant des simulations premiers principes, les signa-tures vibrationnelles et électroniques de certaines unités structurales, abondantes surla surface du verre, sont identifiées. De plus, l’ionicité et la force de divers types de li-aisons sont extraites à partir de ces simulations. Enfin, nous introduisons une méthodenouvelle pour caractériser la structure des liquides et des verres. Notre analyse montreque ces systèmes ont une structure tridimensionnelle étonnamment ordonnée.
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Effects of green light photobiomodulation on Dental Pulp Stem Cells: enhanced proliferation and improved wound healingby cytoskeleton reorganization and cell softening
Auteur(s): Malthiery Eve, Chouaib Batoul, Hernández-López Ana Maria, Martin Fernandez M., Gergely C., Torres Jacques-Henri, Cuisinier Frédéric Jg, Collart Dutilleul Pierre-Yves
(Article) Publié:
Lasers In Medical Science, vol. p. (2020)
Ref HAL: hal-02901458_v1
DOI: 10.1007/s10103-020-03092-1
Exporter : BibTex | endNote
Résumé: Photobiomodulation (PBM) has been shown to improve cell proliferation and cell migration. Many cell types have been
investigated, with most studies using deep penetrating red light irradiation. Considering the interest of surface biostimulation
of oral mesenchymal cells after surgical wound, the present study aimed to assess green light irradiation effects on Dental Pulp
Stem Cells’ (DPSC) proliferation and migration. To understand the mechanisms underlying these effects, we investigated
cytoskeleton organization and subsequent cell shape and stiffness.
A 532-nm wavelength Nd:YAG laser (30 mW) was applied
between 30 and 600 s on DPSC in vitro. Cell proliferation was analyzed at 24, 48, and 72 h after irradiation, by cell counting and enzymatic activity quantification (paranitrophenylphosphate phosphatase (pNPP) test). A wound healing assay was used to study
cell migration after irradiation. Effects of PBM on cytoskeleton organization and cell shape were assessed by actin filaments
staining. Elasticity changes after irradiation were quantified in terms of Young’s modulus measured using Atomic Force
Microscopy (AFM) force spectroscopy. Green light significantly improved DPSC proliferation with a maximal effect obtained after 300-s irradiation (energy fluence 5 J/cm2). This irradiation had a significant impact on cell migration, improving wound
healing after 24 h. These results were concomitant with a decrease of cells’ Young’s modulus after irradiation. This cell softening
was explained by actin cytoskeleton reorganization, with diminution of cell circularity and more abundant pseudopodia. This
study highlights the interest of green laser PMB for the proliferation and migration of mesenchymal stem cells, with encouraging
results for clinical application, especially for surgical wound healing procedures.
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Fused braids and centralisers of tensor representations of Uq(gl(N))
Auteur(s): Crampé N., Poulain d’Andecy Loïc
(Document sans référence bibliographique) 2020-07-01Texte intégral en Openaccess :
Ref HAL: hal-02885777_v1
Exporter : BibTex | endNote
Résumé: We present in this paper the algebra of fused permutations and its deformation the fused Hecke algebra. The first one is defined on a set of combinatorial objects that we call fused permutations, and its deformation on a set of topological objects that we call fused braids. We use these algebras to prove a Schur-Weyl duality theorem for any tensor products of any symmetrised powers of the natural representation of U q (gl N). Then we proceed to the study of the fused Hecke algebras and in particular, we describe explicitely the irreducible representations and the branching rules. Finally, we aim to an algebraic description of the centralisers of the tensor products of U q (gl N)-representations under consideration. We exhibit a simple explicit element that we conjecture to generate the kernel from the fused Hecke algebra to the centraliser. We prove this conjecture in some cases and in particular, we obtain a description of the centraliser of any tensor products of any finite-dimensional representations of U q (sl 2).
Commentaires: 52 pages, 22 ref.
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Modeling the formation and positioning of intracellular macromolecular assemblies: Application to bacterial DNA segregation
Auteur(s): Walter J.-C.
(H.D.R.)
, 2020Texte intégral en Openaccess :
Ref HAL: tel-02893703_v1
Exporter : BibTex | endNote
Résumé: Biology offers new systems for Physics, namely proteins and molecular motors in interaction with biopolymers like DNA and messenger RNA. This field is at the interface between active matter, polymer physics, and physics of colloids. Interestingly, cells also need to increase locally concentrations of proteins in a phase transition-like mechanism to realize vital function like cell division, DNA repair, DNA segregation etc. During this HDR defense, I will offer a physical perspective of intracellular phase transition with the example of bacterial DNA segregation. I will also discuss the motion of ribosomes along messenger RNA, an example of unidimensional inhomogeneous transport giving rise to different dynamical regimes.
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Probing the dynamics of B2O3 across the glass transition: an X-ray photon correlation spectroscopy study
Auteur(s): Martinelli A., Baldi G., Dallari F., Ruffle B., Zontone F., Monaco G.
(Article) Publié:
Philosophical Magazine, vol. p.. (2020)
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Revisiting the Askey–Wilson algebra with the universal R -matrix of Uq(su(2))
Auteur(s): Crampé N., Gaboriaud Julien, Vinet Luc, Zaimi Meri
(Article) Publié:
Journal Of Physics A: Mathematical And Theoretical, vol. 53 p.05LT01 (2020)
Texte intégral en Openaccess :
Ref HAL: hal-02890142_v1
Ref Arxiv: 1908.04806
DOI: 10.1088/1751-8121/ab604e
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé: A description of the embedding of a centrally extended Askey–Wilson algebra, AW(3), in Uq(sl2) 3 is given in terms of the universal R-matrix of Uq(sl2). The generators of the centralizer of Uq(sl2) in its three-fold tensor product are naturally expressed through conjugations of Casimir elements with R. They are seen as the images of the generators of AW(3) under the embedding map by showing that they obey the AW(3) relations. This is achieved by introducing a natural coaction also constructed with the help of the R-matrix.
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Bannai–Ito algebras and the universal R-matrix of osp(1|2)
Auteur(s): Crampé N., Vinet Luc, Zaimi Meri
(Article) Publié:
Letters In Mathematical Physics, vol. 110 p.1043-1055 (2020)
Texte intégral en Openaccess :
Ref HAL: hal-02890130_v1
Ref Arxiv: 1909.06426
DOI: 10.1007/s11005-019-01249-w
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé: The Bannai-Ito algebra BI(n) is viewed as the centralizer of the action of osp(1|2) in the n-fold tensor product of the universal algebra of this Lie superalgebra. The generators of this centralizer are constructed with the help of the universal R-matrix of osp(1|2). The specific structure of the osp(1|2) embeddings to which the centralizing elements are attached as Casimir elements is explained. With the generators defined, the structure relations of BI(n) are derived from those of BI(3) by repeated action of the coproduct and using properties of the R-matrix and of the generators of the symmetric group Sn.
Commentaires: 10 pages, 15 ref.
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