Improved synthesis of functionalized mesogenic 2,6-bisbenzimidazolylpyridine ligands

A versatile one-pot synthetic platform for the preparation of a range of functionalized 2,6-bisbenzimidazolylpyridine (Bip) derivatives is presented. This protocol significantly reduces the cost and time of previous synthetic routes, while facilitating scale up to multi-gram quantities in good yields (63-90%). The previous synthetic methodology was improved through judicious choice of the reducing agent and solvent in the reduction/ring-closing step. Via this platform, we also successfully accessed a mesogenic Bip ligand and herein report initial liquid crystalline properties of this derivative.     

Diffraction of homogeneous and inhomogeneous plane waves on a doubly corrugated liquid/solid interface

This paper extends the theory of the diffraction of sound on 1D corrugated surfaces to 2D corrugated surfaces. Such surfaces, that are egg crate shaped, diffract incoming sound into all polar directions, which is fundamentally different from 1D corrugated surfaces. A theoretical justification is given for extending the classical grating equation to the case of incident inhomogeneous waves, for 1D corrugated surfaces as well as for 2D corrugated surfaces. Even though the present paper presents a theory which is valid for all angles of incidence, special attention is given to the particular case of the stimulation of surface waves by normal incident sound. The most interesting conclusion is that, depending on the frequency and the incident inhomogeneity, Scholte-Stoneley waves and leaky Rayleigh waves can be generated in different directions. This effect might be of particular interest in the development of surface acoustic wave devices and the basic idea of this steering effect can be of importance for planar actuators.     

Diamagnetic interactions between superheated superconducting granules

Within a collection of fixed superheated superconducting granules the fluctuations of the magnetic field are controlled by the geometry. This suggests that the transition, in an applied magnetic field, to the normal state of a suspension of granules does not keep their spatial distribution random. A Monte Carlo simulation for a flat monolayer exhibits a smooth transition from the initial gas-like to the liquid-like distribution. For extreme dilution, a border effect builds up.     

A rapid screening method for prenylated flavonoids with ultra‐high‐performance liquid chromatography/electrospray ionisation mass spectrometry in licorice root extracts

Due to their substitution with an isoprenoid group, prenylated flavonoids have an increased affinity for biological membranes and target proteins, enhancing their potential bioactivity. Although many prenylated flavonoids have been described, there are no methods that specifically screen for their presence in complex mixtures, prior to purification. We describe a method based on ultra‐high‐performance liquid chromatography (UHPLC) with electrospray ionisation mass spectrometry (ESI‐MS) that allows rapid screening for prenylated flavonoids in multi‐component plant extracts. Identification of the prenylated flavonoids is based on screening for neutral losses of 42 u and 56 u in the positive‐ion mode MS² and MS³ spectra within the MS chromatograms. In addition, this method discriminates between a prenyl chain and a ring‐closed prenyl (pyran ring), based on the ratio of the relative abundances of the ions that lose 42 u and 56 u (42:56). The application of this screening method on a 70% aq. ethanol, ethanol and ethyl acetate extract of the roots of Glycyrrhiza glabra indicated the presence of 70 mono‐ and di‐prenylated flavonoids. In addition, of each prenylated flavonoid the type of prenylation, chain or pyran ring was determined. Copyright © 2009 John Wiley & Sons, Ltd.     

Summary of OFC '89, conference on optical fiber communication,February 6–9, 1989, Houston,Texas

The sensitivity of a fiber-optic strain gauge that makes use of interference between the orthogonal linearly polarized eigen-modes propagated in a length of highly birefringent single-mode fiber is primarily determined by tension-induced modal birefiringence ΔB. This ΔB is in a close relationship with the ellipticity of the jacket surrounding the core, on which anisotropic residual stresses are imposed, but ΔB does not depend definitely on the beat length of fiber. Dependence of AB on Young's modulus and the Poisson ratio are computed and discussed in association with the measured results.     

Cyclooctene epoxidation with H2O2 and single crystal X-ray determined crystal structures of new molybdenum and tungsten catalysts bearing the hydrophilic ligand hydroxymethyldiphenylphosphine oxide

The dioxo molybdenum and tungsten complexes MoO₂Cl₂(OPPh₂CH₂OH)₂ and WO₂Cl₂(OPPh₂CH₂OH)₂ have been synthesized and characterized by FT-IR, ¹H and ³¹P NMR. Their structures, as determined by single crystal X-ray diffraction analysis, reveal distorted octahedral geometries with cis terminal oxygen atoms, trans Cl ligands and that the hydroxymethyldiphenylphosphine oxide ligands coordinate through the oxygen atom bonded to the P atom. Both of the compounds are studied as catalysts for the epoxidation of cis-cyclooctene in the presence of hydrogen peroxide as a source of oxygen. Both complexes showed good activity and very high selectivity for the formation of cyclooctene oxide.     

Subcomplexes of mitochondrial complex V reveal mutations in mitochondrial DNA

Complex V, site of the final step in oxidative phosphorylation, uses the proton gradient across the inner mitochondrial membrane for the production of ATP. It is a multi‐subunit complex composed of a catalytic domain (F₁) and a membrane domain (F₀) linked by two stalks. Subcomplexes of complex V containing the F₁ domain have previously been reported in small series of patients. We report the results in tissue samples and/or cultured skin fibroblasts studied by blue native PAGE followed by activity staining in the gel. Catalytically active subcomplexes of complex V were detected in 66 tissues originating from 53 patients. In 29 of the latter (55%), a mitochondrial DNA (mtDNA) defect was identified. Twelve patients had a pathogenic point mutation in a mitochondrial tRNA, one a large mtDNA deletion, 12 showed mtDNA depletion and four had a mutation in the MT‐ATP6 gene. We conclude that the presence of subcomplexes of complex V is a valuable indicator in the detection of mtDNA defects.     

Reduced 1-cohomology and relative property (T)

Shalom characterized property (T) in terms of the vanishing of all reduced first cohomology for compactly generated groups. We characterize group pairs having the property that the restriction map on all first reduced cohomology vanishes. We show that, in a strong sense, this is inequivalent to relative property (T), even for compactly generated group-pairs.