Nicotinic acid complexes with uranyl salts

Summary The potentially bidentate ligand, nicotinic acid, forms 2 : 1 complexes with uranyl chloride, sulphate, nitrate and acetate which have been characterized by i.r. spectral measurements down to 200 cm^–1 in the solid state. These studies indicate conclusively that nicotinic acid coordinates onlyvia its pyridine ring nitrogen in all cases. The uranyl chloride arid sulphate complexes are monomeric hexacoordinated structures, while the nitrate and acetate complexes are octacoordinate around uranium.     

3- and 4-picolylamine complexes of bivalent metal halides and pseudohalides

Summary Coordination compounds formed by the interaction of some bivalent metal halides and pseudohalides with the potentially bidentate ligands, 3-picolylamine and 4-picolyl-amine, have been prepared and characterized by molecular conductance, magnetic susceptibility, electronic and i.r. spectral measurements in the solid state. The i.r. spectral studies indicate that, in addition to their monodentate bonding through pyridine ring nitrogens, these ligands also bond through their amino nitrogen and, in some cases, act as bidentate bridging or chelating ligands. Tentative stereochemistries of the complexes isolated in the solid state are discussed. The ligand field parameters 10 Dq, B, Dq/B, andv ₂/v ₁ are calculated for the cobalt(II) and nickel(II) complexes and are consistent with their proposed stereochemistries.     

2- and 4-benzylpyridine complexes with bivalent metal halides and pseudohalides

Summary Coordination compounds formed by the interaction of 2- and 4-benzylpyridines with some bivalent metal halides and pseudohalides have been prepared and characterized by molecular conductance, magnetic susceptibility, electronic and i.r. spectral measurements down to 200 cm-1 in the solid state. Tentative stereochemistries for the complexes isolated in the solid state are suggested. The ligand-field parameters 10 Dq, B, , and v2 /v, are calculated for the cobalt(II) and nickel(II) complexes and are consistent with their proposed stereochemistries.     

Development of design methods for short cylindrical supersonic exhaust diffuser

Short cylindrical supersonic exhaust diffuser (SED) is needed for use in vertical firing rocket test stands. Design methods are developed and presented in this paper for short SEDs. Incorporation of shock generators further helps in reducing its starting pressure. Received: 9 June 1998/Accepted: 3 October 1999     

Development and Validation of a New Analytical Method for the Determination of Related Components in Quetiapine Hemifumarate

A simple, sensitive isocratic rapid resolution liquid chromatographic assay method has been developed for the quantitative determination of quetiapine hemifumarate in bulk active pharmaceutical ingredient, used for the treatment of schizophrenia. The developed method is also applicable for the process related impurities determination. Efficient chromatographic separation was achieved on a C18 stationary phase with simple mobile phase combination delivered in a isocratic mode and quantification was by ultraviolet detection at 225 nm at a flow rate of 1.0 mL min^?1. In the developed LC method the resolution between quetiapine hemifumarate and its three potential impurities was found to be greater than 2.0. Regression analysis showed an r value (correlation coefficient) greater than 0.99 for quetiapine hemifumarate and its three impurities. This method was capable to detect all three impurities of quetiapine hemifumarate at a level of 0.003% with respect to test concentration of 1.0 mg mL^?1 for a 3 μL injection volume. The bulk active pharmaceutical ingredient was subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation. Considerable degradation was found to occur in oxidative stress conditions. The stress samples were assayed against a qualified reference standard and the mass balance was found close to 99.5%. The developed RR-LC method was validated with respect to linearity, accuracy, precision and robustness.     

Experimental study on mixing enhancement in two dimensional supersonic flow

 Studies on mixing enhancement with two dimensional (2D) lobed nozzle have been conducted in a dual stream supersonic flow facility. The distributions of momentum flux, stagnation pressure and stagnation temperature across a plane at different axial distances from the nozzle exit were considered as a measure of mixing. The results indicated an enormous enhancement in mixing when 2D lobed nozzle was employed in comparison with conventional plain 2D nozzle. The enhanced mixing performance could be attributed to the large scale axial vortices observed in the flow-field of subsonic lobed nozzles by earlier investigators. Received: 27 December 1996 / Accepted: 21 August 1997     

Complexes of some bivalent cobalt,nickel, copper,zinc, cadmium and monovalent silver salts with 4,4′-BipyridylN,N′-dioxide

Summary Coordination compounds have been prepared from 4,4-hipyridylN,N-dioxide (4,4-BipyO₂) and some hivalent metal halides, nitrates and thiocyanates as well as silver(1) nitrate.viz., Co(4.4-BipyO₂)₂Cl₂, Co(4.4-BipyO₂)Br₂, Co(4,4-Bi-pyO₂)(NO₃)₂. Co(4,4-BipyO₂)₂(NCS)₂. Ni(4.4-BipyO₂)₂Cl₂. Ni(4,4-BipyO₂)(NO₃)₂, Ni₂(4.4-BipyO₂)₃(NSC)₄. Cu(4,4-BipyO₂)(NO₃)₂. Zn(4,4-BipyO₂(NO₃)₂, Zn,(4.4-BipyO₂)₃-(NCS)₄. Cd(4.4-BipyO₂)(NO₃)₂, Cd(4.4-BipyO₂)₂(NCS)₂ and Ag(4,4-BipyO₂)(NO₃). The products were characterized by magnetic susceptibility. electronic and i.r. spectral measurements down to 200 cm^–1. Tentative stereochemistries for the complexes isolated in the solid state are proposed. The ligand field parameters 111 Dy. B. j3. )., and calculated for the cobalt. nickel and copper complexes are consistent with these stereochemistries.