Crystal structure of 4,6-dinitro-1-(5-tetrazolyl)-1H-indazole trihydrate

The title compound, C₈H₄N₈O₄·3H₂O, crystallizes in space groupP¯1 with cell constantsa=7.022(1),b=9.507(2),c=10.906(2) Å,=84.99(1),=71.89(1),=72.56(1)°,Z=2, andV _c =660.2 ų. The structure was solved by direct methods using diffractometer data and was refined by full-matrix least-squares methods to anR value of 0.060 for 2112 observed reflections. The molecule, consisting of a phenyl ring fused to a pyrazole ring with a tetrazole ring connected to it equatorially, is planar except for the N(7) nitro-group oxygen atoms. The structure is stabilized by a three-dimensional network of O-HO, O-HN, and N-HO hydrogen bonds through the water molecules.     

Substituted phenothiaziiies as indicators in the ferrocyanide titration of zinc

Chlorpromazine, promethazine and diethazine hydrochlorides and prochlorperazine maleate have been tested as indicators in the ferrocyanide titration of zinc. Only the first and last are useful, giving a sharp reversible colour change in both the direct and reverse titrations, but the results are negatively biased by 0.2-1.3%.     

Interaction of plane turbulent jets in a confined space: mean flow characteristics

The present study deals with the experimental investigations of static pressure and mean velocity fields obtained as a result of the interaction of two plane turbulent jets at impingement angles of α equal to 30° and 45°, with an additional central jet in a confined space. The investigation is carried out for the velocity ratios of U _c/U _o=1.0, 2.0 and 3.0, where U _c and U _o are the velocities in the central plane at the exit of the central jet and the outer jets, respectively. The introduction of the central jet alters the various recirculation zones present in the flow field for all the cases considered above. Also, the change in the velocity ratio U _c/U _o has a significant effect on the pressure and mean velocity flow fields. Flow visualisation results are presented which give a better physical insight into the flow field considered. Received: 26 July 1999/Accepted: 14 February 2000     

Formula for a solution ofu t +H(u,Du) =g

We study the continuous as well as the discontinuous solutions of Hamilton-Jacobi equationu _t +H(u,Du) =g in ℝ ⁿ x ℝ₊ withu(x, 0) =u ₀(x). The HamiltonianH(s,p) is assumed to be convex and positively homogeneous of degree one inp for eachs in ℝ. IfH is non increasing ins, in general, this problem need not admit a continuous viscosity solution. Even in this case we obtain a formula for discontinuous viscosity solutions.