Analysis of a Prototypical Multiscale Method Coupling Atomistic and Continuum Mechanics： the Convex Case

In order to describe a solid which deforms smoothly in some region,but non smoothly in someother region,many multiscale methods have been recently proposed that aim at coupling an atomistic model(discrete mechanics) with a macroscopic model (continuum mechanics).We provide here a theoretical basis forsuch a coupling in a one-dimensional setting,in the case of convex energy.     

Comparative Metabolomic Analysis of Four Fabaceae and Relationship to In Vitro Nematicidal Activity against Xiphinema index

The grapevine fanleaf virus (GFLV), responsible for fanleaf degeneration, is spread in vineyards by the soil nematode Xiphinema index. Nematicide molecules were used to limit the spread of the disease until they were banned due to negative environmental impacts. Therefore, there is a growing interest in alternative methods, including plant-derived products with antagonistic effects to X. index. In this work, we evaluated the nematicidal potential of the aerial parts and roots of four Fabaceae: sainfoin (Onobrychis viciifolia), birdsfoot trefoil (Lotus corniculatus), sweet clover (Melilotus albus), and red clover (Trifolium pratense), as well as that of sainfoin-based commercial pellets. For all tested plants, either aerial or root parts, or both of them, exhibited a nematicidal effect on X. index in vitro, pellets being as effective as freshly harvested plants. Comparative metabolomic analyses did not reveal molecules or molecule families specifically associated with antagonistic properties toward X. index, suggesting that the nematicidal effect is the result of a combination of different molecules rather than associated with a single compound. Finally, scanning electron microscope observations did not reveal the visible impact of O. viciifolia extract on X. index cuticle, suggesting that alteration of the cuticle may not be the primary cause of their nematicidal effect.     

H2O2: a Ca2+ or Mg2+‐sensing function in statin passive diffusion

In a previous paper Guillaume's group demonstrated that magnesium (Mg²⁺ concentration range 0.00–2.60 mm ) increased the passive diffusion of statins and thus played a role in their potential toxicity. In order to confirm an increase in this passive diffusion by divalent salt cations, the role of calcium chloride (CaCl₂) on the statin–immobilized artificial membrane (IAM) association was studied. It was demonstrated that calcium supplementation (Ca²⁺ concentration range 0.00–3.25 mm ) increases the statin passive diffusion. In addition, it was shown that the Ca²⁺ effect on the statin–IAM association is higher than that of Mg²⁺. These results show that Ca²⁺ enhances the passive diffusion of drugs into biological membranes and thus their potential toxicity. Also, addition of H₂O₂ to the medium showed a hyperbolic response for the statin passive diffusion and this effect was enhanced for the highest Ca²⁺ or Mg²⁺ concentrations in the medium. H₂O₂ is likely to interact with the polar head groups of the IAM through dipole–dipole interactions. The conformational changes in H₂O₂–IAM result in a higher degree of exposure of hydrophobic areas, thus explaining why the binding of pravastatin, which showed the lowest logP value, was less affected by H₂O₂. This result shows the significant contribution of H₂O₂ and thus the oxidative stress on the statin passive diffusion. Much of the sensitivity derives from the action of Ca²⁺ or Mg²⁺, in turn supported the idea that H₂O₂ may serve a Ca²⁺ or Mg²⁺ sensing function in statin passive diffusion Copyright © 2015 John Wiley & Sons, Ltd.     

Internal Nucleophilic Termination in Acid‐Mediated Polyene Cyclizations. Part 3

Treatment of the unsaturated allenic alcohols (E)‐ 7 , (Z)‐ 7, 10, 13 , and 19 with an excess of FSO₃H in 2‐nitropropane at ?90° to ?30° afforded, in 68–85% yield, diastereoisomer mixtures of racemic tricyclic ethers 14a – d and 20a – d , respectively (Schemes 3 and 5), with high stereoselectivity (see Table and Scheme 6). These stereospecific transformations represent the first reported examples of an acid‐mediated polyene cyclization, in which an alkene is the initiating group and an allenic alcohol serves as the internal terminator. In close analogy to our earlier work, a nonsynchronous process is postulated, whereby the stereochemical course of cyclization is directed by the conformational structure of an intermediate cyclohexyl cation (see Schemes 3 and 6). In addition, the organoleptic properties of 14c and 20c , racemic didehydro and methyl didehydro analogues, respectively, of the known odorant Ambrox^® ((?)‐ 4f ), are briefly discussed.     

Le théorème de réduction de Marsden-Weinstein en géométrie cosymplectique et de contact

We show that the classical Marsden-Weinstein Reduction theorem for Hamiltonian systems with symmetries is still true for contact manifolds and cosympletic manifolds (i.e. canonical manifolds in the sense of A. Lichnerowicz).

In fact, we precise the notion of transitive almost contact structure, which enables us to consider the cosymplectic geometry as a limit of the contact geometry when a certain parameter goes to zero. This point of view unifies both theories.

However, we have to give two distinct proofs for the contact Reduction theorem and the cosymplectic one.