27 research outputs found
Hyperbolic geometry for non-differential topologists
A soft presentation of hyperbolic spaces, free of differential apparatus, is
offered. Fifth Euclid's postulate in such spaces is overthrown and, among other
things, it is proved that spheres (equipped with great-circle distances) and
hyperbolic and Euclidean spaces are the only locally compact geodesic (i.e.,
convex) metric spaces that are three-point homogeneous.Comment: 14 page
Locally ordered topological spaces
While topology given by a linear order has been extensively studied, this
cannot be said about the case when the order is given only locally. The aim of
this paper is to fill this gap. We consider relation between local orderability
and separation axioms and give characterisation of all connected, locally
connected or compact locally ordered Hausdorff spaces. A collection of
interesting examples is also offered
Chromatographic analysis of ivabradine on polar, nonpolar and chemically modified adsorbents by HPTLC
AbstractThin-layer chromatography (TLC) was used to evaluate the behavior of ivabradine in various chromatographic systems. The mobile phases used were aqueous (methanol–water and acetonitrile–water) and non-aqueous (methanol–acetonitrile and methanol–dimethyl sulfoxide) in a wide range of concentrations (0–100%, v/v). The stationary phases used were high-performance TLC plates: Kieselgel 60 F254 S, RP-2 F254 S, RP-8 F254 S, RP-18 F254 S, RP-18 WF254 S, Kieselgel 60 CN F254 S, Kieselgel 60 Diol F254 S, and Kieselgel 60 NH2 F254 s; and TLC plates: aluminum oxide 150 F254, cellulose F, and polyamide 11 F254. The usefulness of various mobile and stationary phases in the separation of ivabradine was demonstrated. Retention mechanisms as well as the Soczewiński-Snyder equation are discussed