A note on Hydromagnetic oscillatory flow along an infinite flat plate with variable suction

The two-dimensional, incompressible flow past an infinite plate of a weakly conducting fluid in the presence of a transverse magnetic field is discussed when the suction velocity normal to the plate as well as the external flow velocity vary periodically with time. Expressions for the velocity and the skin-friction in the boundary layer have been obtained in a non-dimensional form.     

On the hydromagnetic flow between two parallel,porous plates

This paper deals with the two-dimensional unsteady flow of a conducting viscous incompressible fluid between two parallel, porous plates, one of which is fixed, while the other is uniformly accelerated, when there is a transverse magnetic field. It is shown that, for a given Hartmann number M, as suction parameter β increases, the velocity at any point of the fluid increases, the Skin friction at the stationary plate increases, while that at the accelerated plate decreases. The results are true, as time T increases, for given Hartmann number M and the suction parameter β. The results also hold good for a given β, as M increases when the magnetic lines of force are fixed relative to the plate, while they are just opposite for the magnetic lines of force fixed relative to the fluid.     

Extensive substituent scrambling in substituted diphenylacetylenes on electron impact

Extensive randomization of the substituents is found in mono- and disubstituted diphenylacetylenes under electron impact conditions. The study of diphenylacetylenes with a variety of substituents indicates that the electron-withdrawing groups favour the substituent scrambling, AH the substituted diphenylacetylenes give an ion at m/z 176, having a common ion-structure, arising as a result of the expulsion of a hydrogen radical and the substituent in monosubstituted diphenylacetylenes and the expulsion of both the substituents in disubstituted diphenylacetylenes. A ring-expanded structure is postulated for this common fragment.     

Effective atomic numbers for materials of dosimetric interest

Effective atomic numbers (Z_eff) for different materials of dosimetric interest have been calculated for total photon interaction in the energy region 1 keV–20 MeV. The calculations are made using the mass attenuation coefficients data from Tables of X-ray Mass Attenuation Coefficients and Mass Energy-absorption Coefficients 1 keV to 20 MeV for elements Z = 1 to 92 and 48 Additional Substances of Dosimetric Interest, J. H. Hubbell and S. M. Seltzer (Hubbell and Seltzer, 1995), NISTIR-5632. The variation of Z_eff value with energy is discussed.     

Determination of stoichiometry of cadmium telluride by XPS

Summary The stoichiometry of cadmium telluride has been determined by the non-destructive technique of XPS. The determination has been based on differential photoionisation cross-sections, electron mean free paths and areas due to M₅ electrons of Cd and Te. The stoichiometry of Cd and Te determined by XPS has been found to be in good agreement with that obtained by analysing Cd and Te independently by chemical methods.     

Infra-red spectroscopic studies of solvent-solute interactions in parachlorophenol and thiophenol with tertiary amides

Hydrogen bonding of O-H ... O=C and S-H ... O=C type has been studied in parachlorophenol and thiophenol with dimethyl and diphenyl amides and from the equilibrium constants, variation in the integrated absorption intensities and frequency shifts, the strength of the interaction in these complexes is discussed. In these systems diphenyl amides form weaker H-bond compared to that with the corresponding dimethyl amides. In dimethyl amides, the interaction is in the order dimethyl acetamide > dimethyl propionamide > dimethyl formamide. Similar results are obtained with diphenyl amides.     

Photochemical reduction of thallium(III) with hydrogen peroxide

A convenient method for determination of thallium(III) is based on photochemical reduction with hydrogen peroxide in the presence of bromide as catalyst, followed by oxidation of thallium(I) with potassium bromate.     

Normal vibrations of N,N-dimethylformamide and N,N-dimethylacetamide

Infrared and Raman frequencies of N, N-dimethylformamide and N, N-dimethylacetamide as recorded by the authors, in the region 3100 cm.^?1 to 250 cm.^?1 are given. The normal co-ordinate treatment of these molecules has been carried out using general quadratic force field and the potential energy distribution of the various modes of vibrations have been calculated to study the nature of absorption frequencies arising out of the in-plane vibrations. The assignments made by the authors in the region 3100 cm.^?1 to 500 cm.^?1 are compared with those of Lumley Jones who assigned the frequencies on the basis of band contour studies. These calculations have enabled the authors also to assign the frequencies in the region 500 cm.^?1 to 250 cm.^?1 to the various bending modes of vibrations. The C-N stretching frequency in tertiary amides is considerably different from that in primary and secondary amides.     

Electron-impact-induced hydrogen migration in organic molecules I–Substituent effects in the mass spectra of pivlanilides

Substited pivalanilides give rise to fragments corresponding to anilies on electron-impact, which is due to the migration of a hydrogen atom from the t-butyl group to the nitrogen. The Hammett correlation indicates that the formation of this fragment is favoured by electron-donating groups. The other interesting feature of these spectra is the migration of the aryl group to the t-butyl carbon with the elimination of the neutral ketemine.