The initial single yeast cell adhesion on glass via optical trapping and Derjaguin-Landau-Verwey-Overbeek predictions

We used an optical tweezer to investigate the adhesion of yeast Saccharomyces cerevisiae onto a glass substrate at the initial contact. Micromanipulation of free-living objects with single-beam gradient optical trap enabled to highlight mechanisms involved in this initial contact. As a function of the ionic strength and with a displacement parallel to the glass surface, the yeast adheres following different successive ways: (i) Slipping and rolling at 1.5 mM NaCl, (ii) slipping, rolling, and sticking at 15 mM NaCl, and (iii) only sticking at 150 mM. These observations were numerous and reproducible. A kinetic evolution of these adhesion phenomena during yeast movement was clearly established. The nature, range, and relative intensity of forces involved in these different adhesion mechanisms have been worked out as a quantitative analysis from Derjaguin-Landau-Verwey-Overbeek (DLVO) and extended DLVO theories. Calculations show that the adhesion mechanisms observed and their affinity with ionic strength were mainly governed by the Lifshitz-van der Waals interaction forces and the electrical double-layer repulsion to which are added specific contact forces linked to "sticky" glycoprotein secretion, considered to be the main forces capable of overcoming the short-range Lewis acid-base repulsions.     

Biaryl synthesis via decarboxylative Pd-catalyzed reactions of arenecarboxylic acids and diaryliodonium triflates

A novel simple and efficient synthesis of biaryls via a Pd-catalyzed decarboxylative cross-coupling reaction of arenecarboxylic acids and diaryliodonium triflates is described. The PdCl2/DPEphos catalytic system in the presence of Ag2CO3 in DMSO was found to be the most efficient. Various biaryls, including sterically hindered biaryls, were synthesized with yields ranging from 37 to 85%.     

Local rapid stabilization for a Korteweg–de Vries equation with a Neumann boundary control on the right

This paper is devoted to the study of the rapid exponential stabilization problem for a controlled Korteweg–de Vries equation on a bounded interval with homogeneous Dirichlet boundary conditions and Neumann boundary control at the right endpoint of the interval. For every noncritical length, we build a feedback control law to force the solution of the closed-loop system to decay exponentially to zero with arbitrarily prescribed decay rates, provided that the initial datum is small enough. Our approach relies on the construction of a suitable integral transform and can be applied to many other equations.     

Intégrales orbitales semi-simples et centre de l'algèbre enveloppante

In a previous Note, the first author has established an explicit local formula for semi-simple orbital integrals associated with the Casimir. In this Note, we extend the formula to all elements of the center of the Lie algebra.     

Analysis of a model of phosphorus uptake by plant roots

In this paper, we consider a model of phosphorus uptake by plant roots, governed by a quasilinear parabolic equation. We first study the well posedness of the associated Cauchy problem. Then, we consider a shape optimization problem: how to deform the shape of the root in order to increase phosphorus uptake. Finally, we give some numerical results of the shape optimization process.     

Mean-field games with a major player

We introduce and study mathematically a new class of mean-field-game systems of equations. This class of equations allows us to model situations involving one major player (or agent) and a “large” group of “small” players.