Strong fluctuations near the frustration point in cubic lattice ferromagnets with localized moments

Thermodynamic properties of cubic Heisenberg ferromagnets with competing exchange interactions are considered near the frustration point where the coefficient $D$ in the spin-wave spectrum $E_{\mathbf{k}}\sim D k^{2}$ vanishes. Within the Dyson-Maleev formalism it is found that at low temperatures thermal fluctuations stabilize ferromagnetism by increasing the value of $D$. For not too strong frustration this leads to an unusual "concave" shape of the temperature dependence of magnetization, which is in agreement with experimental data on the europium chalcogenides. The phase diagram is constructed by means of Monte Carlo simulation, and suppression of magnetization and Curie temperature is found in comparison with the results of the spin-wave theory. This effect is explained by the the presence of non-analytical corrections to the spin-wave spectrum which are represented in the lowest order by the term $\sim (T/S)^{2} k^{2}\log{k}$.Comment: 5 pages, 5 figures; updated versio

The Neel temperature and sublattice magnetization for the stacked triangular-lattice antiferromagnet with a weak interlayer coupling

The quantum Heisenberg antiferromagnet on the stacked triangular lattice with the intralayer nearest-neighbor exchange interaction J and interlayer exchange J' is considered within the non-linear $\sigma$-model with the use of the renormalization group (RG) approach. For J' << J the asymptotic formula for the Neel temperature $T_{Neel}$ and sublattice magnetization are obtained. RG turns out to be insufficient to describe experimental data since it does not take into account the $\mathcal{Z}_2$-vortices. Therefore $T_{Neel}$ is estimated using the Monte-Carlo result for the 2D correlation length [10] which has a Kosterlitz-type behavior near the temperature $T_{KT}$ where the vortices are activated.Comment: 4 pages, 1 figur

Method of analysis of particle sedimentation rate in aqueous media

This article deals with the analysis of particle sedimentation velocity in water media with application of video information and pictures management. Kinetics of particles sedimentation in model suspensions and in wastewater were studied by gravimetric method and also by method of video recording of sedimentation with digital photo camera and pictures processing in computer program Adobe Photoshop CS3. In the result of research it was found that analyses of histograms of brightness make it possible to determine particles sedimentation velocity in water media with less time and labor expenditures than in gravimetric method

Analysis of influence of microorganisms on heavy metals adsorption by aluminosilicate sorbents

The article is devoted to the problems of sorption purifying of the water environments polluted by heavy metals ions. The influence of microorganisms on sorption properties of aluminosilicate sorbents is examined. It was studied sorption of Fe 2 + , Cu 2 + ions with bacterial cell in the free state immobilized on a surface of aluminosilicate sorbents and also at formation of biofilms. It is shown that the presence of the immobilized microorganisms increases the limiting capacity of heavy metals sorption by aluminosilicate sorbent. The formation of biofilms on the surfaces of sorbent increases heavy metals resistance of microorganisms and their sorption efficiency in comparison with the aluminosilicate sorbent

Sewage sludge decontamination and methods of its control

In the article it was considered a problem of urban sewage sludge decontamination and meth-ods of its control. It was estimated the efficiency of sludge decontamination under CaO and mi-crowave treatment on the base of determination a total quantity of coliform, thermotolerant coli-form bacteria, mesophilic aerobes and facultative anaerobes, helminth eggs. It was shown that the level of sewage sludge decontamination under microwave treatment at specific energy consumption 0.1 kW·h/kg decreased the amount of sanitary indicative microorganisms, helminth eggs till nominative meanings allowing using non-toxic sewage sludge as fertilizers. It was proposed a biocalorimetric express-method for estimation of sewa ge sludge decontamination that makes it possible to decrease the labor treatment and time of their safety analysis. Comparative estimation of sludge decontamination efficiency showed that MAFAnM index and cell’s heat production are well correlate between each other. It decreases time of sewage sl udge safety analys is from 3 days to 20 min

Realization of anisotropic compass model on the diamond lattice of Cu2+^{2+} in CuAl2_2O4_4

Spin-orbit (SO) Mott insulators are regarded as a new paradigm of magnetic materials, whose properties are largely influenced by SO coupling and featured by highly anisotropic bond-dependent exchange interactions between the spin-orbital entangled Kramers doublets, as typically manifested in $5d$ iridates. Here, we propose that a very similar situation can be realized in cuprates when the Cu$^{2+}$ ions reside in a tetrahedral environment, like in spinel compounds. Using first-principles electronic structure calculations, we construct a realistic model for the diamond lattice of the Cu$^{2+}$ ions in CuAl$_2$O$_4$ and show that the magnetic properties of this compound are largely controlled by anisotropic compass-type exchange interactions that dramatically modify the magnetic ground state by lifting the spiral spin-liquid degeneracy and stabilizing a commensurate single-$\boldsymbol{q}$ spiral

Найменування меблів та хатнього начиння у творах Т. Г. Шевченка та в українських говірках на півночі Молдови

Ігнатенко Д. А. Найменування меблів та хатнього начиння у творах Т. Г. Шевченка та в українських говірках на півночі Молдови / Д. А. Ігнатенко // Одеський лінгвістичний вісник : зб. наук. праць / [голов. ред. Н. В. Петлюченко] ; Нац. ун-т «Одес. юрид. акад.». – Вип. 3.- Спец. вип., присвячений 200-річчю від дня народження Т. Г. Шевченка. – Одеса : Гельветика, 2014. – С. 76-83.У статті представлено результати компаративного аналізу лексики на позначення меблів та хатнього начиння у творах Т.Г. Шевченка та в українських говірках на півночі Молдови