Novel cuticular hydrocarbons from the cane beetle Antitrogus parvulus--4,6,8,10,16-penta- and 4,6,8,10,16,18-hexamethyldocosanes-unprecedented anti-anti-anti-stereochemistry in the 4,6,8,10-methyltetrad

The major cuticular hydrocarbons from the cane beetle species Antitrogus parvulus are 4,6,8,10,16-penta- and 4,6,8,10,16,18-hexamethyldocosanes, 1 and 2, respectively. Stereoisomers of 2,4,6,8-tetramethylundecanal of established relative stereochemistry were derived from 2,4,6-trimethylphenol and were then coupled with appropriate methyl-substituted phosphoranes 62 and 25 to furnish alkenes, which on reduction provided diastereomers of 1 and 2, respectively. Capillary gas chromatography, mass spectrometry, and high resolution 13C NMR spectroscopy confirmed 1 as either 84a or 84b and 2 as either 15a or 15b. The novelty of these structures and their relative stereochemistry is briefly related to polyketide assembly.     

The zwitterion effect in proton exchange membranes as synthesised by polymerisation of bicontinuous microemulsions

The bicontinuous microemulsions consisting of a polymerisable zwitterionic surfactant 3-((11-acryloyloxyundecyl)imidazolyl) propyl sulfonate (AIPS) and other monomers can be cross-polymerised to form good proton conductive membranes.     

Low-loss, wide-angle Y splitter at approximately ~1.6- mum wavelengths built with a two-dimensional photonic crystal

We report a successful experimental realization of a photonic-crystal Y splitter operating at lambda~1.6 mum . Our device has a large splitting angle of 120 degrees and a miniature size of ~3 mumx3 mum . Furthermore, the Y-splitter loss is measured to be 0.5-1 dB at lambda=1640-1680 nm, making the Y splitter promising for integrated photonic-circuit applications. These unique properties are attributed to the new guiding principle made possible by the photonic bandgap.     

An abnormal spin-spin coupling of vinylic-allylic protons generated by a constraint of configuration

In a system where a rigid or frozen conformation constrains an allylic proton to orient nearly perpendicular to the plane of the olefinic bond, the allylic spin coupling may become comparable to, or greater than, the vicinal spin coupling. This anomalous situation is demonstrated in three series of compounds: the adducts of diazoalkanes to 1,2-diazepines, 4-piperidinocycloalk-2-en-1-one oximes and heterobicyclo[3,2,0]hept-3,6-dienes, where the NMR spectra have been well established by decoupling experiments.     

The effect of bloch-wall motion on the flow stress of nickel single crystals

Experimental evidence is presented that moving Bloch-walls decrease the flow stress of nickel single crystals. Via their strain fields, Block-walls interact with dislocations.