Studies on the mixing of two non-axial jets in a confined passage — turbulence characteristics

The mean characteristics of the flow due to mixing of two non-axial plane jets in a confined passage, were reported previously by Manjunath et al. (Exp. Fluids 11 (1991), 17–24), as part I. In this paper, the turbulence characteristics of the flow are discussed. The various components of the Reynolds stress tensor are reported for the four inlet angles considered, viz., 15°, 30°, 45° and 60°. As expected from the mean flow field, the inlet angle influences the distribution of the various turbulence components through the relative size of the recirculation zones and the turbulence field is different for the smaller angles of 15° and 30° in comparison to those for 45° and 60°.     

Determination of unsteady heat release distribution from acoustic pressure measurements: a reformulation of the inverse problem

An integral method is developed to solve the inverse problem of determining the oscillatory heat release distribution from the knowledge of the acoustic pressure field within a combustor. Unlike earlier approaches, in which the problem is formulated in terms of Fredholm integral equation, the inverse problem is reformulated in terms of Volterra integral equation. This reformulation, valid for low Mach numbers (M2 < 1), facilitates the recovery of heat release at all frequencies. The resulting Volterra integral equation is solved using both direct numerical method and implicit least-squares method. The results show that the implicit least-squares method is superior to the direct numerical method and yields accurate determination of heat release at all frequencies.     

Indirect spectrophotometric determination of propranolol hydrochloride and piroxicam in pure and pharmaceutical formulations.

Two simple and sensitive indirect spectrophotometric methods for the assay of propranolol hydrochloride (PPH) and piroxicam (PX) in pure and pharmaceutical formulations have been proposed. The methods are based on the oxidation of PPH by a known excess of standard N-bromosuccinimide (NBS) and PX by ceric ammonium sulfate (CAS) in an acidic medium followed by the reaction of excess oxidant with promethazine hydrochloride (PMH) and methdilazine hydrochloride (MDH) to yield red-colored products. The absorbance values decreased linearly with increasing concentration of the drugs. The systems obeyed Beer's law over the concentration ranges of 0.5 - 12.5 and 0.3 - 16.0 microg/ml for PPH, and 0.4 - 7.5 and 0.2 - 10 microg/ml for PX with PMH and MDH, respectively. Molar absorptivity values, as calculated from Beer's law data, were found to be 1.36 x 10(4) and 2.55 x 10(4) l mol(-1) cm(-1) for PPH, and 2.08 x 10(4) and 2.05 x 10(4) l mol(-1) cm(-1) for PX with PMH and MDH, respectively. The common excipients and additives did not interfere with their determinations. The proposed methods have been successfully applied to the determinations of PPH and PX in various dosage forms. The results obtained by the proposed methods compare favorably with those of official methods.     

Conversion from a π to a σ structure on replacing oxygen by sulphur: an ESR study

The radical cations of 1,3-dioxacylohexane and 1,3-dioxacyclopentane have π-structures involving delocalisation within the [-OCH₂O-]⁺ unit with high spin-density on the CH₂ group, whilst, in complete contrast, the corresponding sulphur derivatives have a weak σ bond between the two sulphur atoms, the unpaired electron being in the σ^* orbital with negligible spin-density on the CH₂ group.     

Mixed metal complexes of iron-molybdenum with 8-quinolinolate and dithiocarbamates

Summary Iron-molybdenum heterometallic complexes, FeMoO₂R₄-(H₂O) (R=8-quinolinolate, diethyldithiocarbamate, 4-morpholinyl-dithiocarbamate and piperidinyldithiocarbamate), have been prepared from iron(III) molybdate. T.l.c. and x-ray diffraction studies indicate that the complexes are discrete species. The complexes are non-electrolytes in dimethylformamide. Magnetic measurements suggest that the iron and molybdenum are in the III and V oxidation states, respectively, with octahedral geometry around each atom. I.r. spectral studies indicate the presence of MoO³⁺ and FeOMo bridges and the monoionic bidentate nature of the ligands. Electronic spectral and thermal decomposition studies on these complexes are reported.