Extraction of the (C4H9)4N+Co(II)SCN− ion-pair in chloroform and in isoamyl alcohol: Spectrophotometric determination of cobalt

When excesses of ammonium thiocyanate and tetrabutylammonium chloride are added to a cobalt(II) solution, a water-insoluble ion-pair is formed; this compound is soluble in chloroform, isoamyl alcohol, and other solvents. The variables which affect the extractions by these two solvents are studied in order to obtain the optimal conditions and two alternative extraction procedures are proposed. Thus, the separation of cobalt as a previous step for its spectrophotometric determination is studied.     

Sections and projections of nested convex bodies

Aequationes mathematicae - One of the most important problems in Geometric Tomography is to establish properties of a given convex body if we know some properties over its sections or its...     

The crystal structure of eudesma-4(15),7(11)-dien-8α, 12-olide: a sesquiterpene lactone fromTrattinickia rhoifolia Willd

The title compound, formula C₁₅H₂₀O₂, is orthorhombic, P2₁2₁2₁ witha=8.747(2),b=12.025(3),c=12.554(3)Å,Z=4, andD _m =1.32(2)g/ml. The structural analysis shows that the compound corresponds to eudesma-4(15),7(11)-dien-8,12-olide, a sesquiterpene lactone previously isolated fromAster umbellatus but whose crystal structure was unknown.     

Individual extraction constants of some dicarbollylcobaltate anions in the water-nitrobenzene system

Individual extraction constants of nine dicarbollylcobaltate anions in the two-phase water-nitrobenzene system were determined radiometrically assuming that the changes of Gibbs energy of the transfer of the tetraphenylarsonium cation, Ph₄As⁺, and of the tetraphenylborate anion, BPh ₄ ^– , from the aqueous into the nitrobenzene phase are equal. The constants obtained by this method were correlated with Hansch's constants of hydrophobity.     

Topologically nontrivial field configurations in noncommutative geometry

In the framework of noncommutative geometry we describe spinor fields with nonvanishing winding number on a truncated (fuzzy) sphere. The corresponding field theory actions conserve all basic symmetries of the standard commutative version (space isometries and global chiral symmetry), but due to the noncommutativity of the space the fields are regularized and they contain only a finite number of modes.Part of the Project P8916-PHY of the Fonds zur Förderung der wissenschaftlichen Forschung in Österreich.