On the vibrational spectra of liquid HCl

We report quantitative measurements of the infrared spectra intensities and of the Raman cross section for liquid HCl. The local field effect and the induced dipole moment account for the observed intensity enhancement. Our calculation is based on the reaction field approach. On the other hand, we show that the local field effect and the dipolar term in the intermolecular interaction energy are not sufficient to explain the frequency shift. We also show that the first overtone is mainly due to simultaneous transitions of two molecules from the ν = 0 to the ν = 1 levels and our calculations give the right order of magnitude of its intensity. Finally, we can reproduce the lineshape of the first overtone by a dissipative coupling which is derived from Redfield's theory of relaxation.     

Viscosity behavior of poly(glyceryl methacrylate) in the presence of borate and phenylboronate ions

The viscosity behavior of polyelectrolyte solutions induced by borate or phenylboronate complexation with poly(glyceryl methacrylate) (PGM) has been investigated. In dilute solutions borate ions can form monodiol (1/1) complexes and didiol (2/1) intramolecular complexes. Both types of complex are anionic. Thus, the polymer is characterized by the existence of charged sites on the chain and loops formed by intramolecular complexation. On the contrary, phenylboronate can only give monodiol 1/1 complexes. In the presence of passive salt, the charges are screened. By addition of borate ion to a PGM solution, a decrease of the initial polymer viscosity due to loop formation is first observed, then the anionic charges fixed on the chain by complex formation induce an expansion of the polyelectrolyte and the viscosity of the solution increases. The situation is different for the PGM-phenyl boronate system, where no intramolecular crosslink is present. In this case the viscosity of the solution increases with phenyl boronate concentration. But for a fixed complexing ion concentration it will tend to that of the neutral polymer when NaCl is added. ©1995 John Wiley & Sons, Inc.     

Determination of dietary fibre by the AOAC method in raw and processed vegetables: peas samples

Summary Total dietary fibre was determinated by the enzymatic gravimetric method of the AOAC in raw and processed (autoclaved and microwave heated) peas. Pods were also analyzed. The importance of the corrections for protein and ash proposed by the AOAC method were confirmed. Starch content in the TDF residues is also reported.     

Synthesis of n,n′-biquinolines by a coupling reaction of bromoquinolines using organonickel(0) complexes

Tris(triphenylphosphine)nickel(0) (A) and a zerovalent pyridine–nickel complex (B) have been used as reagents for the coupling reaction of 3-, 6- and 8-bromoquinolines: 3,3′-, 6-6′- and 8,8′- Biquinolines were obtained in quantitative yields when A was used as the coupling reagent. B gave always a mixture of the n,n′ -biquinoline and substitution products. A mechanism can be outlined to explain the coupling reaction of bromoquinolines using zerovalent nickel complexes.     

An n.m.r. study on displacements from platinum(II) complexes by dimethylsulphoxide

Summary Substitutions of platinum(II) complexes with nitrogen donors by the soft sulphur donor dimethylsulphoxide (DMSO) were studied by n.m.r. spectroscopy and quantum-mechanical calculations.The results indicate that the softness of halide as well as the affinities of the displaced ligands influence the substitution processes.     

Structural properties of Si and GaP

Total energies are calculated for crystalline Si and GaP within the local-density functional formalism using first principles non-local pseudopotentials. Ground state structural properties (total energy, bulk modulus and lattice constant) are obtained for Si and GaP and are in good agreement with experimental values (differences < 6%). Si is used as a test and compared with other theoretical calculations.