Biomedical subjects

F Argoul

Publications and source records attributed to F Argoul.

At least 19 recordsLinked to original sources

PubMed2005

Electrically induced microflows probed by fluorescence correlation spectroscopy.

We report on the experimental characterisation of electrically induced flows at the micrometer scale through Fluorescence Correlation Spectroscopy (FCS) measurements. We stress the potential of FCS as a useful characterisation technique in microfluidics devices for transport properties cartography. The experimental results obtained in a model situation are in agreement with previous calculations (F. Nadal, F. Argoul, P. Kestener, B. Pouligny, C. Ybert, A. Ajdari, Eur. Phys. J. E 9, 387 (2002)) predicting the structure and electric-field dependency of the induced flow. Additionally, the present study evidences a complex behaviour of the probe nanobeads under electric field whose precise understanding might prove relevant for situations where nano-objects interact with an external electric field.

Electrochemistry↗

PubMed2004

Low frequency rhythms in human DNA sequences: a key to the organization of gene location and orientation?

We explore large-scale nucleotide compositional fluctuations of the human genome using multiresolution techniques. Analysis of the GC content and of the AT and GC skews reveals the existence of rhythms with two main periods of 110+/-20 kb and 400+/-50 kb that enlighten a remarkable cooperative gene organization. We show that the observed nonlinear oscillations are likely to display all the characteristic features of chaotic strange attractors which suggests a very attractive deterministic picture: gene orientation and location, in relation with the structure and dynamics of chromatin, might be governed by a low-dimensional nonlinear dynamical system.

AT Rich Sequence↗

PubMed2002

Electrically induced flows in the vicinity of a dielectric stripe on a conducting plane.

We report a theoretical and experimental study of the hydrodynamic flow induced by an a.c. electric field in the vicinity of a dielectric stripe deposited on a conducting plate. In the theoretical part, we model the stripe as a small change of the surface capacitance of the plate, and a perturbative approach is used to perform the calculations. This approach predicts an outwards rectified electro-osmotic slip along the surface that generates two steady counter-rotating rolls, the size of which decreases with the frequency. In the experimental section, we use tracers to determine the structure of the flow and investigate its dependence on the frequency and the amplitude of the applied voltage. The structure and amplitude of the observed flow compares satisfactorily with the theoretical analysis. This could guide the design of surface-controlled flows and help to understand the collective behavior of colloids near electrodes.

Journal Article↗

PubMed2000

Dense branching morphology in electrodeposition experiments: characterization and mean-field modeling

Dense branching morphologies (DBM) obtained in thin gap electrodeposition cells are characterized by a dense array of branches behind a flat advancing envelope. In this Letter, we show the existence in DBM of a new (porous) phase, qualitatively different from a (compact) metal deposit. The local porosity inside the branches is found to be much more robust than geometric characteristics such as the width or the distance between branches. This fact seems to be unreported in previous modeling of DBM. A mean-field model is proposed that displays overall features observed in the experiments, such as concentration profiles, front velocity, and branched internal structure.

Journal Article↗

PubMed2000

Internal structure of dense electrodeposits

We report experimental investigations of the structure of dense patterns obtained during electrochemical deposition of copper in thin cells. The deposit correlation function reveals the periodic structuration of the patterns but shows that the primary spacing is not steady during the growth and that moreover it is not simply related to the diffusion length. Another measurable quantity is the occupancy ratio of the fingers in the cell. Its variation as a function of the experimental parameters is interpreted from specific properties of electrochemical growth. The results are discussed with respect to the well-known behavior of cellular solidification fronts.

Journal Article↗

PubMed1996