Pattern formation and spatial self-entrainment in bistable chemical systems

We describe the formation of spatial structures generated by diffusive instabilities in bistable systems. The coupling between the different spatial modes emanating from the two homogeneous steady states can then give rise to self-parametric instabilities favoring the occurrence of resonant rhombic or quasiperiodic structures such as superlattices or quasicrystalline patterns.     

A superior method for the reduction of secondary phosphine oxides

[reaction: see text] Diisobutylaluminum hydride (DIBAL-H) and triisobutylaluminum have been found to be outstanding reductants for secondary phosphine oxides (SPOs). All classes of SPOs can be readily reduced, including diaryl, arylalkyl, and dialkyl members. Many SPOs can now be reduced at cryogenic temperatures, and conditions for preservation of reducible functional groups have been found. Even the most electron-rich and sterically hindered phosphine oxides can be reduced in a few hours at 50-70 degrees C. This new reduction has distinct advantages over existing technologies.     

New potential materials for infrared nonlinear optics. Preparation, characterisation and optical transparency of monometallic and bimetallic iodates

The non-centrosymmetric compounds Mg(IO₃)₂, Mn(IO₃)₂, Co(IO₃)₂ and Zn(IO₃)₂ are isostructural and crystallise in space-group type P2₁ with a pseudo-hexagonal lattice leading to the formation of a three-individual twin by pseudo-merohedry. Because of this structural analogy, solid solutions are possible between these metallic iodates. Bimetallic iodates Mn_1−xZn_x(IO₃)₂ form a solid solution over the entire domain of composition. Second harmonic generation test and absorption studies carried out on theses materials show high nonlinear activities, high damage thresholds and are transparent up to 12 μm in the IR.     

Interfacial stress analysis of functionally graded beams strengthened with a bonded hygrothermal aged composite plate

This paper reports an improved analytical solution for analysis the problem of interface stresses in functionally graded beam (FGB) strengthened with bonded hygrothermal aged composite plates. The material properties of the functionally graded beam are supposed to vary according to power law distribution of the volume fraction of the constituents through the beam thickness. The obtained results are compared with the existing solutions in the literature to verify the validity of the new analytical approach. It is found that the inhomogeneities play an important role in reducing the stress concentrations along bi-material interfaces. Finally, a parametric study was carried out to show the effects of the fiber volume fraction, the hygrothermal effect, and some design variables, e.g. thickness of adhesive layer and FRP plate on the magnitude of maximum shear and normal stress.     

High-Resolution FTIR Spectra of CD2Cl2: Analysis of the ν3/ν7/ν9 Triad

The infrared spectra of isotopically pure CD₂³⁵Cl₂ have been recorded at a resolution of 0.0026 cm⁻¹ (FWHM) in the range 600-1160 cm⁻¹ with a Bruker IFS 120 HR Fourier transform interferometer. The absorption between 670 and 750 cm⁻¹ is due to three fundamentals, ν₃ (weak), ν₇ (very weak), and ν₉ (strong). A satisfactory analysis of the observed spectra has been obtained by including a c-Coriolis coupling between ν₃ and ν₉ and a b-Coriolis term between ν₇ and ν₉. Although no transitions could be observed for the very weak ν₇ band, its band origin could be estimated from the Coriolis interaction with ν₉. From the analysis of about 4200 assigned transitions of the ν₃ and ν₉ bands, excited state constants have been determined up to sextic terms. The Coriolis parameters obtained are compared to those calculated from a harmonic force field.     

Square Integrable Representations,von Neumann Algebras and An Application to Gabor Analysis

Let G be a locally compact group, and let be a lattice in G. Let (, H ) be an irreducible, square integrable unitary representation of G. Then the restriction of to extends to VN(), the von Neumann algebra generated by the regular representation of . We determine the center valued (or extended) von Neumann dimension of H as a VN()-module. This result is extended to representations which are square integrable modulo the center of G. An explicit formula is given when G is a semisimple algebraic group and when G is a nilpotent Lie group. As an application, we study the question of the existence of frames for the discretized windowed Fourier transform.     

Spatial multistability and nonvariational effects

We investigate the phenomenon of spatial multistability of fronts in thin bistable systems and stress the important role played by the absence of a variational principle. Nonvariational effects allow, for instance, two different immobilized fronts to coexist. The morphological instability of the corresponding nucleating solution can then lead, even in the absence of any diffusive instability, to nontrivial patterns in the depth of one-side-fed reactors.     

Diarylnonanoids and their glucosides from Erica cinerea

The reinvestigation of Erica cinerea fresh aerial parts led to the isolation of two new diarylnonanoid aglycones along with their glucosides. From spectroscopic data, their structures were elucidated as rel-(3R,7R)-1,9-bis(p-hydroxyphenyl)-3,7-dihydroxynonan-5-one named ericanone, ericanone 3-β-d-glucoside, (3S)-3,7-anhydro-6,7-dehydroericanone and (3S)-3,7-anhydro-6,7-dehydroericanone 4′-β-d-glucoside. Contrary to the numerous diarylheptanoids more frequently distributed in the plant kingdom, the rare diarylnonanoids were previously restricted to the genus Myristica of the Myristicaceae plant family.