On the distribution of the number of real zeros of a random polynomial

In this note, we find the distibution of the number of real zeros of a random polynomial. We also derive a formula for the expected number of complex zeros lying in a given domain of the complex plane. Bibliography: 7 titles. __________ Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 320, 2004, pp. 69–79.     

Solid-phase reagent for molecular spectroscopic determination of heavy metal speciation in natural water

A solid-phase reagent based on 1-(4-adamantyl-2-thiasolylazo)-2-naphthol adsorbed onto silica gel was prepared for Co(II) recovery and preconcentration prior to its sorption-spectroscopic detection. The immobilized reagent was applied to the determination of free cobalt ions in natural water. The solid-phase reagent and chemiluminescent method coupled with membrane filtration, gel-permeation and ion-exchange chromatography were applied to the study of the speciation of iron and cobalt in water from the Dnieper reservoirs and lakes of Kyiv City; their predominant forms were complexes of Fe(III) and Co(II) with dissolved organic matter and fulvic acids play a main role in their complexation.     

Analytical Application of Silica Gel Modified with Didecylaminoethyl-beta-Tridecylammonium Iodide

Sorption of a high molecular weight quaternary ammonium salt, didecylaminoethyl-β-tridecylammonium iodide (DDATD) on different types of sorbents was investigated. The nature of reagent adsorption on silica gel was examined by spectroscopic and computer methods. The sorption of anionic metal complexes of cobalt, copper, zinc and manganese on silica gel modified with DDATD was studied. The possibility of recovery of cobalt and copper thiocyanate complexes and their further atomic absorption determination is shown. Modified sorbent was applied to cobalt chemiluminescence and determined in natural water and a nickel preparation (detection limit, 2 μg/l.).     

Determination of Ag(I), Hg(II) and Pb(II) by using silica gel loaded with dithizone and zinc dithizonate

The modified sorbents with dithizone and zinc dithizonate adsorbed on the silica surface were obtained. The adsorption of heavy metal ions from aqueous solutions onto loaded silicas was studied. Color scales for Ag(I), Hg(II) and Pb(II) visual test detection were worked out. The modified silica gels were established to be applicable to semi-quantitative determination of these metal ions in buttermilk, natural, mineral and waste water.     

Ordered structures based on self-organized Au and CdSe nanoparticles

Methods for obtaining cadmium selenide and gold nanoparticles have been developed. The sizes of the nanoparticles are determined and the morphology, structure, and chemical composition of these nanoparticles and their ensembles are studied by a complex of structural methods: electron diffraction, X-ray diffraction, energy-dispersive X-ray analysis, high-resolution transmission electron microscopy, and small-angle X-ray scattering. Gold nanoparticles are mainly spherical and have an average size of 10 nm. They are single-phase and have an fcc crystal structure. Samples of synthesized CdSe nanoparticles contain monodisperse spherical particles 12 nm in size with a wurtzite structure. The deposition of nanoparticles on a carbon substrate is accompanied by their self-organization into a closely packed two-dimensional structure with a pronounced texture in which all nanoparticles are oriented in the [001] direction perpendicularly to the carbon substrate plane.     

Synthesis, fluorescent properties and aggregation of 2,3-dihydroisoindolenylcalix[4]arenes

New derivatives of calix[4]arenes, containing two isoindole fragments in distal positions of the macrocycle upper rim were synthesized. According to NMR and molecular modeling data, the obtained calixarenes exist in “flattened cone” conformation with inclination angles of benzene rings to the macrocycle plane equal to 133–140° and 92–100°. Fluorometric studies showed the presence of self-aggregation of isoindolenylcalixarenes in acetone solutions starting from micromolar concentrations.     

Zinc oxide nanoparticles immobilized on graphene flake

Interactions of ZnO nanoparticles with graphene oxide in isopropanol were studied; graphene oxide was shown to perform as an efficient substrate to immobilize zinc oxide nanoparticles on its surface. Interactions of nanocomposites consisting of graphene oxide-zinc oxide nanoparticles with supercritical isopropanol were studied. The conversion of graphene oxide into graphene does not appreciably changes the composition, morphology, or structure of ZnO nanoparticles.     

Synthesis of cobalt-containing nanoparticles by cobalt formate thermolysis in hydrocarbon oil without stabilizing ligands

A simple and available method is proposed for the synthesis of cobalt-containing nanoparticles. This method comprises cobalt formate thermolysis in hydrocarbon oil without extra stabilizing ligands. The size, composition, and structure of the nanoparticles are determined by transmission electron microscopy, X-ray powder diffraction, and electron diffraction. The average particle size is 10–14 nm. The major components are cobalt oxides CoO and Co₃O₄. Apart from these oxides, the particles contain minor metallic cobalt.