Vol. 42 No. 3 (217) (2008)

The influence of initial concentrations of reagents: sodium acrylate, potassium persulfate, two marks of polyvinylalcohol (PVA) as well medium pH and temperature on the polymerization rate, has been studied. The study of initiation mechanism making use the inhibitory method, has been established that the kinetic regularities are due to the participation of associates, which are being formed between monomer and PVA in elementary steps of chain propagation and termination. The solubility dependence of obtained polymer samples as well their water absorption extent on temperature has been studied too.

The present work refers to the introduction of hydrophilic vitamin-B₆ in hydrophobe matrix of polystyrene as a new model for drug formulation. The transfer of vitamin from polystyrene matrix to aqua phase is investigated by using absorption spectroscopy. Entering of hydrophilic vitamin into the hydrophobe membrane was performed by lecithin. The proposed model can be used for external use drug formulation.

The complexformation of methionine (Met) with cobalt ion in aqueous solutions has been investigated by IR spectroscopy and kinetic methods. It has been shown that two types: 1:1 and 2:1 complexes are formed between the ligande and metal ion. In the system 1:1 complex predominates, which have catalytic activity on the cumene hydroperoxide (CHP) decomposition in aqueous solutions, where a reaction between Met and CHP takes place. The kinetic law of hydroperoxide (ROOH) catalytic decomposition at the presence of [CoMet]²⁺ complex is found: W₀ = –d[ROOH]/dt = K_cat[Co²⁺]₀[Met][ROOH]₀ = K_eff[ROOH]₀. Temperature dependence of K_eff  is expressed by the following equation: K_eff = (1.12 ± 0.05)105exp[(–43000 ± 300)/RT], min^–1.

By the methods of UV spectroscopy and theoretical conformational analyses was investigated the structural peculiarities of DNA at complexformation with cis-DDP at extremal pH medium (pH< 4, pH>9). It was shown that by ionization of nitrogen bases, significant changes in T_m(pH) and ΔT(pH) take place. However, DNA-cis-DDP bidental interstand crosslink model and formation of chelates does not play а prior role at the platination.

The effect of various lactoserum, nutrient compounds and growth conditions (temperature, time) upon the cultivation of lactobacteria and their antibacterial properties was studied. The obtained supernatants were shown to have different antibacterial activity and sensibility to temperature.

In the article data about distribution of Uredinales in the Republic of Nagorny Karabakh are presented. As a result of investigations 63 species from 9 genera of Uredinales are found. They are parasites on 61 species of wild plants and 12 species of cultivated plants. The widely-distributed species belonged to genera Puccinia (36 species) and Uromyces (11 species).

The interaction of mercuro-ion with thiourea has been studied by means of potentiometric and amperometric titration methods. The molar ratio (1:2) of the reacting components has been determined. The optimal concentrations of the sulfuric and nitric acids have been revealed: correspondingly 0.1–2 M and 0.1–6 M. The combination of the two methods – potentiometric and amperometric, creates a possibility to determine mercuro-ion within wide range of concentrations (5·10^-5 – 7·10^-2 М).

The specific structure of trees and bushes of some parks of Yerevan City is studied. Most widespread kinds of wood and shrubs breeds are noted. We propose to increase assortment of green plantings at the expense of coniferous kinds, trees blossoming in the early spring and kinds of lianas. To turn a close attention to spreading the tree-of-heaven in parks the high degree of germination of its seeds, stirs to normal growth of other trees and bushes, and also grassy plants.