Ref HAL: hal-01058494_v1
Ref Arxiv: 1408.6085
DOI: 10.1021/ac501115y
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23 Citations
Résumé:

Taylor dispersion analysis is an increasingly popular characterization method that measures the diffusion coefficient, and hence the hydrodynamic radius, of (bio)polymers, nanoparticles or even small molecules. In this work, we describe an extension to current data analysis schemes that allows size polydispersity to be quantified for an arbitrary sample, thereby significantly enhancing the potentiality of Taylor dispersion analysis. The method is based on a cumulant development similar to that used for the analysis of dynamic light scattering data. Specific challenges posed by the cumulant analysis of Taylor dispersion data are discussed, and practical ways to address them are proposed. We successfully test this new method by analyzing both simulated and experimental data for solutions of moderately polydisperse polymers and polymer mixtures.

Commentaires: 41 pages (including Supporting Information), 5 figures (+ 7 figs. in the Supporting Information)

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PMID 24920407
Ref Arxiv: 1403.4433
DOI: 10.1039/c4sm00531g
WoS: 000341025700007
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91 Citations
Résumé:

We use a custom shear cell coupled to an optical microscope to investigate at the particle level the yielding transition in concentrated emulsions subjected to an oscillatory shear deformation. By performing experiments lasting thousands of cycles on samples at several volume fractions and for a variety of applied strain amplitudes, we obtain a comprehensive, microscopic picture of the yielding transition. We find that irreversible particle motion sharply increases beyond a volume-fraction dependent critical strain, which is found to be in close agreement with the strain beyond which the stress-strain relation probed in rheology experiments significantly departs from linearity. The shear-induced dynamics are very heterogenous: quiescent particles coexist with two distinct populations of mobile and 'supermobile' particles. Dynamic activity exhibits spatial and temporal correlations, with rearrangements events organized in bursts of motion affecting localized regions of the sample. Analogies with other sheared soft materials and with recent work on the transition to irreversibility in sheared complex fluids are briefly discussed.

Commentaires: 11 pages, 10 figures. Submitted to Soft Matter

Ref HAL: hal-01101065_v1
Ref Arxiv: 1408.5357
DOI: 10.1088/1742-5468/2014/11/P11032
WoS: 000345747600032
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42 Citations
Résumé:

We study the matrix ansatz in the quantum group framework, applying integrable systems techniques to statistical physics models. We start by reviewing the two approaches, and then show how one can use the former to get new insight on the latter. We illustrate our method by solving a model of reaction-diffusion. An eigenvector for the transfer matrix for the XXZ spin chain with non-diagonal boundary is also obtained using a matrix ansatz.

Commentaires: 44 pages

Ref HAL: hal-01057398_v1
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I present an overview of the recent results and open problems in finding the non-perturbative effective action for compactifications of type II string theory on Calabi-Yau manifolds.

Ref HAL: hal-01056398_v1
DOI: 10.1117/12.2040529
WoS: 000337347500018
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2 Citations
Résumé:

We report on the development of a novel class of nanowire-based THz detectors in which the field effect transistor (FET) is integrated in a narrow-band antenna. When the THz field is applied between the gate and the source terminals of the FET, a constant source-to-drain photovoltage appears as a result of the non-linear transfer characteristic of the transistor. In order to achieve attoFarad-order capacitance we fabricate lateral gate FET with gate widths smaller than 100 nm. Our devices show a maximum responsivity of 110 V/W without amplification, with noise equivalent power levels <= 1 nW/root Hz at room temperature. The 0.3 THz resonant antenna has bandwidth of similar to 10 GHz and opens a path to novel applications of our technology including metrology, spectroscopy, homeland security, biomedical and pharmaceutical applications. Moreover the possibility to extend this approach to relatively large multi-pixel arrays coupled with THz sources makes it highly appealing for a future generation of THz detectors.

Résumé:

Physical modeling of viral assembly

Ref HAL: hal-01054237_v1
DOI: 10.1209/0295-5075/107/30006
WoS: 000340780100006
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3 Citations
Résumé:

We present a new model to realize artificial 2D lattices with cold atoms investigating the atomic artificial graphene: a 2D confined matter wave is scattered by atoms of a second species trapped around the nodes of a honeycomb optical lattice. The system allows an exact determination of the Green function, hence of the transport properties. The inter-species interaction can be tuned via the interplay between scattering length and confinements. Band structure and density of states of a periodic lattice are derived for different values of the interaction strength. Emergence and features of Dirac cones are pointed out, together with the appearance of multiple gaps and a non-dispersive and isolated flat band. Robustness against finite-size and vacancies effects is numerically investigated.