Influence of environmental conditions on the interfacial organisation of fengycin, a bioactive lipopeptide produced by Bacillus subtilis

The effect of the environmental conditions both on the behaviour of fengycin at the air-aqueous interface and on its interaction with DPPC was studied using surface pressure-area isotherms and AFM. The ionisation state of fengycin is at the origin of its monolayer interfacial properties. The most organised interfacial arrangement is obtained when fengycin behaves as if having zero net charge (pH 2). In a fully ionised state (pH 7.4), the organisation and the stability of fengycin monolayers depend on the ionic strength in the subphase. This can modulate the surface potential of fengycin and consequently the electrostatic repulsions inside the interfacial monolayer, as well as the lipopeptide interaction with the layer of water molecules forming the air-water interface. Intermolecular interactions of fengycin with DPPC are also strongly affected by the ionisation state of lipopeptide and the surface pressure (Pi) of the monolayer. A better miscibility between both interfacial components is observed at pH 2, while negatively charged lipopeptide molecules are segregated from the DPPC phase. A progressive desorption of fengycin from the interface is observed at pH 7.4 when Pi increases while at pH 2, fengycin desorption brutally occurs when Pi rises above Pi value of the intermediate plateau.     

BSDEs with two RCLL reflecting obstacles driven by Brownian motion and Poisson measure and a related mixed zero-sum game

In this paper we study Backward Stochastic Differential Equations with two reflecting right continuous with left limit obstacles (or barriers) when the noise is given by Brownian motion and a mutually independent Poisson random measure. The jumps of the obstacle processes could be either predictable or inaccessible. We show the existence and uniqueness of the solution when the barriers are completely separated and the generator uniformly Lipschitz. We do not assume the existence of a difference of supermartingales between the obstacles. As an application, we show that the related mixed zero-sum differential–integral game problem has a value.     

Ice sliding games

This paper deals with sliding games, which are a variant of the better known pushpush game. On a given structure (grid, torus...), a robot can move in a specific set of directions, and stops when it hits a block or boundary of the structure. The objective is to place the minimum number of blocks such that the robot can visit all the possible positions of the structure. In particular, we give the exact value of this number when playing on a rectangular grid and a torus. Other variants of this game are also considered, by constraining the robot to stop on each case, or by replacing blocks by walls.     

Submicrometer digital in-line holographic microscopy at 32 nm with high-order harmonics

Soft-x-ray digital in-line microscopic holography is achieved using a fully coherent high-order harmonic source emitting at 32 nm. Combination of commercial-grade soft-x-ray optics and a back-illuminated CCD detector allows a compact and versatile holographic setup. Different experimental geometries have been tested by imaging calibrated 50 nm tips and 1 microm wires. Spatial resolution of 800 nm is measured with magnifications ranging from 30 to 110 and a numerical aperture around 0.01. Finally, the potentiality of three-dimensional numerical reconstruction from a single hologram acquisition is shown experimentally.     

Formate Oxidase (FOx) from Aspergillus oryzae: One Catalyst Enables Diverse H2O2‐Dependent Biocatalytic Oxidation Reactions

An increasing number of biocatalytic oxidation reactions rely on H₂O₂ as a clean oxidant. The poor robustness of most enzymes towards H₂O₂, however, necessitates more efficient systems for in situ H₂O₂ generation. In analogy to the well‐known formate dehydrogenase to promote NADH‐dependent reactions, we here propose employing formate oxidase (FOx) to promote H₂O₂‐dependent enzymatic oxidation reactions. Even under non‐optimised conditions, high turnover numbers for coupled FOx/peroxygenase catalysis were achieved.     

Rheological properties of gluten plasticized with glycerol: dependence on temperature, glycerol content and mixing conditions

The rheological behaviour of a gluten plasticized with glycerol has been studied in oscillatory shear. The mixing operation in a Haake batch mixer leads to a maximum torque for a level of specific energy (500–600 kJ/kg) and temperature (50–60 °C) quite independent of mixing conditions (rotor speed, mixing time, filling ratio). The gluten/glycerol dough behaves as a classical gluten/water dough, with a storage modulus higher than the loss modulus over the frequency range under study. A temperature increase induces a decrease of moduli, but the material is not thermorheologically simple. Glycerol has a plasticizing effect, which can be classically described by an exponential dependence. Mixing conditions influence the viscoelastic properties of the material, mainly through the specific mechanical energy input (to 2000 kJ/kg) and temperature increase (to 80 °C). Above 50 °C, specific mechanical energy highly increases the complex modulus. The aggregation of proteins, as evidenced by size-exclusion chromatography measurements, occurs later as the dough temperature reaches 70 °C. The nature of network interactions and the respective influence of hydrophobic and disulphide contribution is discussed. A general expression is proposed for describing the viscous behaviour of a gluten/glycerol mix, which could seem simplistic for such a complex rheological behaviour, but would remain sufficient for modelling the flow behaviour in a twin screw extruder. Received: 24 November 1997 Accepted: 28 April 1999     

Non-broken circuits of reflection groups and factorization inD n

The set of non-broken circuits of a reflection group W, denoted NBC(W), appears as a basis of the Orlik-Solomon algebra ofW. The factorization of their enumerating polynomial with respect to their cardinality involves the exponentsd _i-1 ofW. A simple explanation of this factorization is known only for the symmetric groupsS _n (Whitney [13]) and for the hyperoctahedral groupsB _n (Lehrer [7]). In this paper, we present an elementary proof of the fact that the set NBC(W) of any refection groupW is in bijection with the group elements ofW. We give a simple characterization of the non-broken circuits of the Weyl groups of typeD _n and we use this characterization to prove the factorization of their enumerating polynomial. Work partially supported by FGIA from ASU. Work partially supported by NSERC (Canada).     

A Branch and Bound algorithm for minimizing the energy consumption of an electrical vehicle

The problem we address in this paper, is the minimization of the energy consumption of an electrical vehicle achievable on a given driving cycle. This can be formulated as an optimal control problem with a discrete switch control. In this paper, we present a new formulation of this problem by taking into account the electrical and mechanical parts of the vehicle. By using prototype optimal control shooting techniques, we did not provide efficient solutions. Consequently, we focused on an operational method based on a Branch and Bound algorithm to solve this optimal switching control problem. Some numerical experiments validate our methodology.     

Switching problem and related system of reflected backward SDEs

This paper studies a system of backward stochastic differential equations with oblique reflections (RBSDEs for short), motivated by the switching problem under Knightian uncertainty and recursive utilities. The main feature of our system is that its components are interconnected through both the generators and the obstacles. We prove existence, uniqueness, and stability of the solution of the RBSDE, and give the expression of the price and the optimal strategy for the original switching problem via a verification theorem.     

A Remark on an Algebraic Riemann—Roch Formula for Flat Bundles

Let f:X S be a smooth projective morphism over an algebraically closed field, with X and S regular. When E, ) is a flat bundle over X, then its Gauss–Manin bundles on S have a flat connection and one may ask for a Riemann–Roch formula relating the algebraic Chern–Simons and Cheeger–Simons invariants. We give an answer for X = Y × S, f = projection. The method of proof is inspired by the work of Hitchin and Simpson.