On geodesic mappings of equidistant generalized Riemannian spaces

In this paper geodesic mappings of equidistant generalized Riemannian spaces are discussed. It is proved that each equidistant generalized Riemannian space of basic type admits non-trivial geodesic mapping with preserved equidistant congruence. Especially, there exists non-trivial geodesic mapping of equidistant generalized Riemannian space onto equidistant Riemannian space. An example of geodesic mapping of an equidistant generalized Riemannian spaces is presented.     

On the total mean curvature of piecewise smooth surfaces under infinitesimal bending

Variation of the total mean curvature of piecewise smooth surfaces in Euclidean 3-spaces under infinitesimal bending is discussed and reduced to a sum of line integrals of a rotation vector field.     

Development and Evaluation of a Kinetic‐Spectrophotometric Method for Determination of Arginine

A kinetic method for the determination of micro quantities of amino acid arginine (Arg) is described in this paper. The catalytic activity of cobalt in the reaction of oxidation of purpurin (1,2,4‐trihydroxy‐antraquinone, PP) by hydrogen peroxide in alkaline buffer solution decreases in the presence of micro quantities of arginine, because of the formation of the complex. Operating conditions for the successful determination of arginine were optimized. The optimized conditions yielded a theoretical detection limit of 1.45 μg mL^?1. Kinetic equations are proposed for the investigated process. The interference effects of certain foreign ions and amino acids upon the reaction rate were studied and removed in order to assess the selectivity of the method. The developed procedure was successfully applied to the determination of arginine in various pharmaceutical samples. The typical feature of this procedure is that determination can be carried out at room temperature and in a short analysis time. The newly developed method is simple, inexpensive and efficient for use in the analysis of a large number of samples.     

On Equitorsion Holomorphically Projective Mappings of Generalized Kählerian Spaces

In this paper we investigate holomorphically projective mappings of generalized Kählerian spaces. In the case of equitorsion holomorphically projective mappings of generalized Kählerian spaces we obtain five invariant geometric objects for these mappings.     

Studies Directed Towards Stereospecific Synthesis of Oxybiotin,Biotin, and Their Analogs. III. Preparation of Some New 2,5-Anhydro-Xylitol Derivatives

Abstract

Some new partially or fully tosylated and/or mesylated 2, 5-anhydro-xylitol derivatives have been prepared in this work. Some of them represent the real optically active intermediates in an attempted synthesis of selected (+)-oxybiotin analogs, while the others, being racemic, serve only as easily available model-intermediates.     

Rigidity and flexibility analysis of a kind of surfaces of revolution and visualization

In this paper we consider a class of toroids generated by a meridian in a shape of quadrangle in an arbitrary position to the axis of revolution.We give geometrical meaning of the non-rigidity condition based on the position of the diagonals of meridian. Special classes of quadrangular meridians (trapezium, parallelogram, deltoid, … ) are discussed. The number of flexible toroids is considered. A tool SurfBend is developed for the rigidity and visualization.     

Equitorsion holomorphically projective mappings of generalized Kählerian space of the first kind

In this paper we define generalized Kählerian spaces of the first kind (\(G_1^K N\)) given by (2.1)–(2.3). For them we consider hollomorphically projective mappings with invariant complex structure. Also, we consider equitorsion geodesic mapping between these two spaces (\(G_1^K N\) and \(G_1^{\bar K} N\)) and for them we find invariant geometric objects.     

Some Invariants of Equitorsion Third Type Almost Geodesic Mappings

Mediterranean Journal of Mathematics - In this paper, we consider equitorsion third type almost geodesic mappings of non-symmetric affine connection spaces. Applying different computational...     

Coulometric bipotentiometric titration of bases and their mixtures in acetic anhydride in the presence of two pretreated metal (Au,Pd)- quinhydrone electrodes

Summary The possibility of application of gold and palladium as the metal phase of quinhydrone electrodes in coulometric bipotentiometric titrations of bases alone and of some of their two-component mixtures in acetic anhydride was investigated. The effect of activation of these electrodes, by heating in an alcohol flame, on the shape of the titration curve is discussed. The amounts of bases determined were 5.0–10.0 eq. Errors did not exceed ±2%.

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Zusammenfassung Die Möglichkeit der Verwendung von Gold und Palladium als Metallphase von Chinhydronelektroden bei coulometrischen bipotentiometrischen Titrationen von Basen allein oder Gemischen zweier Basen in Essigsäureanhydrid wurde untersucht. Der Einfluß der Aktivierung dieser Elektroden durch Glühen in einer Alkoholflamme auf die Form der Titrationskurve wurde diskutiert. Die Mengen der analysierten Basen entsprach 5,0–10,0 Mikroäquivalenten. Die Ermittlungsfehler liegen innerhalb ± 2%.