NMR investigation of concentrated alumina and silica slurries

The longitudinal relaxation times (T₁) of water in concentrated silica and alumina slurries were measured as a function of solids content. It was shown that the results could be fit very well with a two-phase fast-exchange model between free and surface-bound water. As expected, values of T₁ for bound water were in the order of 20–2000 times lower than that for free water, indicating a higher effective viscosity of the surface-bound water. The strength of the interaction depended on the particular surface, and all of the aluminas examined interacted more strongly with water than the two silicas studied, which themselves differed considerably. The chemical mechanical polishing (CMP) removal rate of tantalum by silica slurries was shown to be directly correlated with the interaction parameters, derived from the NMR relation times rather than with total surface hydroxyl group concentration.     

Economics and Performance of 10 Gb/s Metro Transport Over Mixed Fiber Plant of G.655 NZDF and G.652.C Zero Water-Peak Fibers

Using lower-cost lasers, 30% savings are possible for 10-Gb/s uncompensated metro transmission over NZDF, compared to G.652 fiber. We present WDM transmission results for a mixed plant of NZDF rings interconnected to G.652.C-fiber access laterals.     

From the Boltzmann equation to the Stokes‐Fourier system in a bounded domain

We prove that the renormalized solutions of the Boltzmann equation considered in a bounded domain with different types of (kinetic) boundary conditions converge to the Stokes‐Fourier system with different types of (fluid) boundary conditions when the main free path goes to zero. This extends the work of F. Golse and D. Levermore [9] to the case of a bounded domain. © 2003 Wiley Periodicals, Inc.     

Silylation partielle et réduction de composés gem-polychlorés fonctionnels

The trimethylchlorosilane/magnesium/hexamethylphosphoric triamide (HMPT) system reacts with some functional polychlorinated compounds (chloral, hexachloroacetone, acetone chloroform) affording a partial reduction accompanied by silylation and leads to new functional silylated derivatives.These reactions exhibit reductive properties of magnesium, in HMPT, towards the CCl bond.     

Syntheses of 3,7-dimethylpentadecan-2-ols from intermediates formed from co-oligomerisation reactions of butadiene with diethyl malonate and acetaldehyde

The products of the reaction of butadiene with diethyl malonate catalysed by a palladium complex and of butadiene with acetaldehyde catalysed by a nickel(0) complex have been used in two syntheses of 3,7-dimethylpentadecan-2-ol.     

Structures cristallines et moléculaires des muscs macrocycliques III. La muscone et sa 2,4-dinitrophénylhydrazone

Crystal and Molecular Structure of Macrocyclic Musks. III. Muscone and its 2, 4-Diuitrophenylhydrazone Muscone (3-methylcyclopentadecanone C₁₆H₃₀O) forms orthorhombic plastic-crystals with Z = 2 (a = 5.560(4), b = 8.176(6), c = 17,168(20) Å). Single crystals are obtained by zone melting at 258 °K. The high degree of disorder and the ambiguity of space group have precluded a structural determination by X-ray diffraction methods. The crystal structure of muscone 2,4-dinitrophenylhydrazone (DNPHM; C₂₂H₃₄N₄O₄, triclinic, space group P¯, a = 8.015 (4), b = 8.235 (2), c = 17.409 (4) Å. α = 102.69 (4), β; = 93.86 (3), γ = 96.03 (3)° Z = 2) was solved by direct methods and refined to a final R of 0.155 (R_ω = 0.102). The macrocycle shows static disorder, which could be partially resolved by analysis of the anisotropy of the atomic vibrational parameters. Eight possible conformers with reasonable geometries emerged from the subsequent refinements and were used as starting models in force-field calculations, which converged to four quinquangular conformations ([25233]; [34233]; [21423*4]; [3423*4]) with similar energies. In the molecular packing, the interactions between macrocycles and substituents are minimized. They are comparable to those described for the cis- and trans-civetone DNPH derivatives [1] [2].