A conductometric immunosensor based on functionalized magnetite nanoparticles for E. coli detection

We report a new approach for immunoassays based on magnetite nanoparticles for Escherichia coli (E. coli) detection using conductometric measurements. Biotinylated antibodies, anti-E. coli, were immobilized on streptavidin modified magnetite nanoparticles by biotin–streptavidin interaction. A layer of functionalized nanoparticles were directly immobilized on the conductometric electrode using glutaraldehyde cross-linking.The specific test with E. coli cells and the non specific test using Staphylococcus epidermidis (S. epidermidis) were investigated by conductometric measurements. Results show a good response as a function of antigen additions. The detection of 1 CFU/ml of E. coli induces a conductivity variation of 35 μS. The negative test shows good selectivity using the conductometric immunosensor. Conductometric measurements allow to detect 500 CFU/l.     

A conductometric biosensor for the estimation of the number of cleaving sites in peptides and proteins

A conductometric enzyme biosensor using proteinase K was developed and then tested to relate its electrical signal to the number of proteinase K hydrolysis sites in bovine serum albumin (BSA) and angiotensin, a ten amino acid peptide, with one cleaving site.The conductometric sensor presents a large linear range of response for BSA and angiotensin ranging from 0.5 to 8 mg/l and from 4 to 8 mg/l, respectively. For a same tested concentration (mg/l), the response for native BSA is 12 times higher than for angiotensin. Aspartam was used as negative test and no response was obtained with the proteinase K biosensor. The conductometric sensor permitted also to detect difference on enzyme activity on native and non-native BSA, a response three times higher was obtained for non-native BSA.     

On closed anti de Sitter spacetimes

This article deals with the structure of the fundamental group of compact anti de Sitter spacetimes, i.e. Lorentz manifolds with constant negative curvature. Algebraically such a manifold is the quotient of the universal cover of the homogeneous space by a discrete group acting properly and co-compactly on it. This exists if and only if is even. Indeed, as this was observed by Kulkarni, is contained in , and acts properly transitively on . It then suffices to take as a co-compact lattice in . The results of the present article give evidence to the question: in dimension , are all compact anti de Sitter spacetimes constructed in this way? Received: 18 May 1996 / Revised version: 3 January 1997     

On lightlike geometry: isometric actions,and rigidity aspects

Degenerate Riemannian metrics exist naturally in various contexts. Unfortunately, their study stops to the ‘admission of failure’ that they are too poor, for instance, to generate a coherent intrinsic or extrinsic differential geometry, e.g. a kind of Levi-Civita connection. In this first text, we start the investigation of rigidity aspects of these structures, from the point of view of isometric actions of ‘big’ (e.g. semi-simple) Lie groups. To cite this article: E. Bekkara et al., C. R. Acad. Sci. Paris, Ser. I 343 (2006).     

Impulsive stochastic functional differential inclusions driven by a fractional Brownian motion with infinite delay

In this paper, we prove the existence of mild solutions for a first‐order impulsive semilinear stochastic functional differential inclusions driven by a fractional Brownian motion with infinite delay. We consider the cases in which the right hand side is convex or nonconvex valued. The results are obtained by using two different fixed point theorems for multivalued mappings. Copyright © 2015 John Wiley & Sons, Ltd.     

From the mathematical kinetic theory for active particles on the derivation of hyperbolic macroscopic tissue models

This paper deals with the derivation of macroscopic equations from the underlying kinetic model delivered by the kinetic theory of active particles with discrete microscopic states. Hyperbolic models for local density and mean velocity are obtained with the aim at adding further knowledge to mathematical methods for modelling living matter.     

Global solution to the Cauchy problem for discrete velocity models of vehicular traffic

This paper offers the proof of the existence for large times of the Cauchy problem for a class of vehicular traffic models with discrete velocities derived from the mathematical tools of the kinetic theory for active particles. This approach has the ability to capture some basic aspects concerning the complexity of the systems under consideration through an appropriate modeling, via stochastic games, of the interactions at the microscopic scale. The proof is related to specific aspects of the real system and hopefully can contribute towards improving the modeling approach.