Ref HAL: hal-01363957_v1
DOI: 10.1002/wcms.1277
WoS: 000399010400002
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Résumé:

Organic–inorganic interactions are of high importance in several biological pro- cesses and in modern nanobiotechnological applications. Despite its signifi- cance in interface sciences, the basic mechanism of biomolecules’ specific binding to a surface is still not well understood. Current experimental methods have not reached the level either to follow the dynamics of interactions at the picosecond scale or to observe the surface morphology at the nanoscale level. The increasing interest in bio-interfaces particularly for engineering applica- tions demands proteins or peptides to be designed to recognize the inorganic surface with high specificity. Molecular simulation has been well adopted in the past couple of decades to decipher the protein–surface interactions at differ- ent levels of time and length scales. Several molecular simulation methods such as quantum mechanics, atomistic, and coarse grain simulations were employed in this domain of research, but the continuous improvements in interfacial force field (FF) development, availability of experimental data and new sampling methods make the atomistic simulation more attractive due to the offered accu- rate representation of protein adsorption behavior at the atomic level. However, the exactitude of such simulations entirely depends on the applied FF para- meters, conformational sampling, and the solvation effects. In this overview, we briefly summarize the applicability of different simulation methods and of interface FFs. We also present the recent advances in the simulation of protein– surface interactions, and the challenges posed by the current simulation meth- ods to reproduce the exact phenomenon. Future directions in this research field are also discussed.

Ref HAL: hal-01363227_v1
DOI: 10.1364/OE.24.026887
WoS: 000388414600089
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11 Citations
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An original technique that combines digital holography, dual illumination of the sample and cleaning algorithm 3D reconstruction is proposed. It uses a standard transmission microscopy setup coupled with a digital holography detection. The technique is 4D, since it allows to determine, at each time step, the 3D locations (x, y, z) of many moving objects that scatter the dual illumination beam. The technique has been validated by imaging the microcirculation of blood in a fish larvae sample (the moving objects are thus red blood cells RBCs). Videos showing in 4D the moving RBCs superimposed with the perfused blood vessels are obtained.

Ref HAL: hal-01362938_v1
DOI: 10.1103/PhysRevLett.117.097402
WoS: 000382008400011
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30 Citations
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We report on the ultraviolet optical response of a color center in hexagonal boron nitride. We demonstrate a mapping between the vibronic spectrum of the color center and the phonon dispersion in hexagonal boron nitride, with a striking suppression of the phonon assisted emission signal at the energy of the phonon gap. By means of nonperturbative calculations of the electron-phonon interaction in a strongly anisotropic phonon dispersion, we reach a quantitative interpretation of the acoustic phonon sidebands from cryogenic temperatures up to room temperature. Our analysis provides an original method for estimating the spatial extension of the electronic wave function in a point defect.

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PMID 27601100
DOI: 10.1021/acs.jpclett.6b01709
WoS: 000384966500012
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51 Citations

Ref HAL: hal-01360538_v1
Ref Arxiv: 1511.04201
DOI: 10.1073/pnas.1607730113
WoS: 000380346200037
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55 Citations
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Low-temperature properties of crystalline solids can be understood using harmonic perturbations around a perfect lattice, as in Debye's theory. Low-temperature properties of amorphous solids, however, strongly depart from such descriptions, displaying enhanced transport, activated slow dynamics across energy barriers, excess vibrational modes with respect to Debye's theory (i.e., a Boson Peak), and complex irreversible responses to small mechanical deformations. These experimental observations indirectly suggest that the dynamics of amorphous solids becomes anomalous at low temperatures. Here, we present direct numerical evidence that vibrations change nature at a well-defined location deep inside the glass phase of a simple glass former. We provide a real-space description of this transition and of the rapidly growing time and length scales that accompany it. Our results provide the seed for a universal understanding of low-temperature glass anomalies within the theoretical framework of the recently discovered Gardner phase transition.

Commentaires: 12 pages, 20 figures. Accepted for publication in PNAS. Réf Journal: PNAS 113, 8397-8401 (2016)

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Ref Arxiv: 1604.05532
DOI: 10.1063/1.4959034
WoS: 000381679800009
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7 Citations
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We employ a field-theoretical variational approach to study the behavior of ionic solutions in the grand canonical ensemble. To describe properly the hardcore interactions between ions, we use a cutoff in Fourier space for the electrostatic contribution of the grand potential and the Carnahan-Starling equation of state with a modified chemical potential for the pressure one. We first calibrate our method by comparing its predictions at room temperature with Monte Carlo results for excess chemical potential and energy. We then validate our approach in the bulk phase by describing the classical “ionic liquid-vapor” phase transition induced by ionic correlations at low temperature, before applying it to electrolytes at room temperature confined to nanopores embedded in a low dielectric medium and coupled to an external reservoir of ions. The ionic concentration in the nanopore is then correctly described from very low bulk concentrations, where dielectric exclusion shifts the transition up to room temperature for sufficiently tight nanopores, to high concentrations where hardcore interactions dominate which, as expected, modify only slightly this ionic “capillary evaporation.”

Ref HAL: hal-01360270_v1
Ref Arxiv: 1602.07524
DOI: 10.1103/PhysRevLett.116.176801
WoS: WOS:000374964400010
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39 Citations
Résumé:

By numerical simulations and analytical studies, we show that the phenomenon of microwave-induced resistance oscillations can be understood as a classical memory effect caused by re-collisions of electrons with scattering centers after a cyclotron period. We develop a Drude-like approach to magneto-transport in presence of a microwave field, taking account of memory effects, and find an excellent agreement between numerical and analytical results, as well as a qualitative agreement with experiment.

Commentaires: 6 pages, 3 figures. Réf Journal: Phys. Rev. Lett. 116, 176801 (2016)