High efficiency of superacid HF-SbF5 for the selective decrystallization-depolymerization of cellulose to glucose

Herein, we show that after polyprotonation, superacid HF-SbF(5) is able to selectively depolymerise cellulose to water-soluble carbohydrates with 68 wt% yield of glucose. This process is efficient at low temperature, thus avoiding the formation of side products as commonly observed with conventional acids.     

Triterpenoid saponins from berries of Hedera colchica.

Fifteen triterpenoid saponins were isolated from the berries of Hedera colchica and their structures established on the basis of chemical and spectroscopic evidence. Among them, two are new compounds: coichiside A (3) and colchiside B (15) and four are described for the first time in the berries of Hedera colchica (compounds 1, 8, 9 and 11).     

Stroboscopy

The history and principles of stroboscopy are reviewed, and stroboscopic findings during videolaryngoscopy are evaluated in relationship to the rest of the laryngological clinical evaluation to arrive at the bases for a stroboscopic semiology     

Theoretical modelling of S-band thulium-doped silica fibre amplifiers

A comprehensive numerical model of a thulium-doped silica-based fibre amplifiers is presented. The model is spectrally and spatially resolved and is general in terms of pumping scheme used. The application of the model for predicting the S-band amplifier performance and for optimization of amplifier parameters is shown. For optimized Tm-doped fibre with ³H₄ level lifetime of 45 μs, which is the maximum value in the Tm-doped silica fibres prepared by the authors, above 20 dB of gain with 2000 mW pump power at the 1050 nm pump band can be expected according to the simulations.     

Synthesis, photophysical and nonlinear optical properties of macromolecular architectures featuring octupolar tris(bipyridine) ruthenium(II) moieties: evidence for a supramolecular self-ordering in a dentritic structure

The synthesis, photophysical and nonlinear optical properties of several new multi-octupolar tris(bipyridine) ruthenium complexes are reported. The preparation on these complexes is based on the initial construction of multipodal 4,4'-dialkylaminostyryl-2,2'-bipyridine ligands (DAAS-bpy). Thermally stable polyimides featuring octupolar ruthenium trisbipyridyl complexes have been readily obtained by a polycondensation reaction. The controlled coordination strategy of dipodal and tripodal bipyridines to ruthenium(II) has also been successfully used to build bimetallic, trimetallic as well as the first metallodendrimer made of seven metallo-octupoles. These polymetallic species exhibit very intense absorption bands in the visible and long-lived luminescence. The quadratic NLO-susceptibilities beta of these macromolecules have been characterized by harmonic light scattering at 1.91 microm and compared with those of the corresponding monometallic species. The NLO studies clearly demonstrates a quasi-supramolecular ordering in the metallodendrimer.