Establishing the fundamental magnetic interactions in the chiral skyrmionic Mott insulator Cu2OSeO3 by terahertz electron spin resonance

The recent discovery of skyrmions in Cu$_2$OSeO$_3$ has established a new platform to create and manipulate skyrmionic spin textures. We use high-field electron spin resonance (ESR) spectroscopy combining a terahertz free electron laser and pulsed magnetic fields up to 64 T to probe and quantify its microscopic spin-spin interactions. Besides providing direct access to the long-wavelength Goldstone mode, this technique probes also the high-energy part of the excitation spectrum which is inaccessible by standard low-frequency ESR. Fitting the behavior of the observed modes in magnetic field to a theoretical framework establishes experimentally that the fundamental magnetic building blocks of this skyrmionic magnet are rigid, highly entangled and weakly coupled tetrahedra.Comment: 5 pages, 3 Figure

Evaluation of hepatotoxic properties of pyrimidine derivatives

The aim of the study was to evaluate the hepatotoxic properties of new pyrimidine derivatives 3-[2-(1-naphthyl)-2- oxoethyl]-6-bromoquinazoline-4(3H)-oh (VMA–13–06), 3-(2-tert-butyl-2-oxoethyl)quinazoline-4(3H)-one (VMA-13- 11) and 3-(2-isopropyloxy-2-oxoethyl)quinazoline-4(3H)-oh (VMA-13-12). Material and methods. The study was carried out on male rats, which were divided into four groups: control receiving an intragastrically distilled water and experimental groups of animals receiving intragastrically suspended in distilled water pyrimidine compounds VMA- 13-06, VMA-13-11 and VMA-13-12 at doses of 1/10 of the molecular weight (39, 24 and 24 mg/kg respectively) for 60 days. In order to assess possible toxic damage to the liver, blood biochemical parameters were evaluated: alanine aminotransferase, aspartate aminotransferase, gamma-glutamyltransferase, alkaline phosphatase activity, total protein, albumin, total and free bilirubin content. Results. There were no statistically significant changes in total protein, albumin, total and free bilirubin after administration of VMA–13–06 and VMA–13–11 in comparison with the control group. The VMA–13–12 compound contributed to an increase in total and free bilirubin content by 43 % (p < 0.01) and 90 % (p < 0.01), while the increase in the concentration of total protein and albumin did not have any statistical significance. The analysis of enzyme parameters also indicates the absence of hepatocyte damage with the introduction of VMA- 13-06 and VMA-13-11: alanine aminotransferase, aspartate aminotransferase, gamma-glutamyltransferase, alkaline phosphatase activity did not change. VMA–13–12 administration led to an increase in enzyme activity in comparison with the control: alanine aminotransferase – by 59 % (p < 0.01), aspartate aminotransferase – by 28 % (p < 0.05), gamma- glutamyltransferase – by 46 % (p < 0.01), alkaline phosphatase – by 31 % (p < 0.05). Conclusions. We established the absence of hepatotoxic properties of pyrimidine derivatives 3-[2-(1-naphthyl)-2-oxoethyl]-6-bromoquinazoline-4(3H)- oh and 3-(2-tert-butyl-2-oxoethyl)quinazoline-4(3H)-oh. Compound 3-(2-isopropyloxy-2-oxoethyl)quinazoline-4(3H)- oh has a hepatotoxic effect, accompanied by a decrease in protein-synthesizing and detoxifying liver function

First-principles study of structural, electronic and thermodynamic properties of (ZnO)n_n(n=2-16) clusters

The structural, electronic, and vibrational thermodynamic properties of the (ZnO)$_n$ (n=2-16) clusters are studied using density functional - full potential computations. The results show, small clusters up to $n=9$ stabilize in the 2D ring shape geometries while the larger clusters prefer the 3D cage like structures. The ring to cage structural cross over in ZnO clusters is studied by investigating the behavior of the Zn-O-Zn bond angle, the Zn-O bond strength, and the number of bonds in the systems. It is argued that 12 is the lowest magic number of ZnO clusters at ground state, while finite temperature vibrational excitations enhance the relative stability of the (ZnO)$_9$ cluster and make it a magic system at temperatures above about 170 K. The obtained electronic structure of ZnO clusters before and after applying the many-body GW corrections evidence a size induced red shift originated from the ring to cage structural cross over in these systems. The behavior of the extremal points of electron density of the clusters along with the extrapolated cluster binding energies at very large sizes may be evidences for existence of a metastable structure for large ZnO nanostructures, different with the bulk ZnO structure.Comment: 8 pages, 8 figures and 1 tabl

International trends in the justice digitalization development

The authors substantiate the feasibility of introducing digital technology into the modern system of administration of justice. It is noted that the introduction of digital technologies will reduce the time for disposal of legal proceedings, create an independent, but at the same time transparent judicial system, improve the quality of decisions taken by the court and the level of public confidence in the state, and minimize government spending in this are

Strange Exotic States and Compact Stars

We discuss the possible appearance of strange exotic multi-quark states in the interior of neutron stars and signals for the existence of strange quark matter in the core of compact stars. We show how the in-medium properties of possible pentaquark states are constrained by pulsar mass measurements. The possibility of generating the observed large pulsar kick velocities by asymmetric emission of neutrinos from strange quark matter in magnetic fields is outlined.Comment: 10 pages, invited talk given at the International Conference on Strangeness in Quark Matter 2006 (SQM2006), UCLA, USA, March 26-31, 2006, Journal of Physics G in press, refs. adde

CHOICE OF CONDITIONS FOR GAS OUTFLOW IN VACUUM AND CONFIGURATIONS OF A FORMING UNIT FEEDING A WORKING SUBSTANCE INTO THE PLASMA VOLUME

The paper presents formulated requirements to the gas-dynamic device designed for working substance feeding into the ionization zone of plasmas facilities. The role of geometrical factors in formation of a supersonic flow is determined, as well as, the role of gasdynamic factors in attainment of necessary parameters beyond the forming element. The conditions for gas-dynamic flow clustering minimization in the course of outflow in vacuum

Synchronization of breathing and aiming skills as a Basis for training rifle shooters at a moving target

Objective of the study was to develop a pedagogical model for training rifle shooters at a moving target based on the synchronization of breathing and aiming skill

Screening studies of antimicrobial activity of pyrimidine derivative

Aim of the study was to screen the antimicrobial activity of pyrimidine derivative 3-[2-(1-naphthyl)-2-oxoethyl]-6-bromoquinazoline-4(3H)-oh with laboratory cipher VMA–13–06 in relation to pathogenic and opportunistic flora. Material and methods. Antimicrobial activity of VMA–13–06 was established in vitro against strains of Staphylococcus aureus, Klebsiella pneumonia, Streptococcus pyogenes, Escherichia coli, Acinetobacter baumannii and Citrobacter freundii by the method of serial dilutions, by forming rows with different concentrations of the compound under study. Results. VMA–13–06 was found to exhibit high antibacterial activity against S. aureus, S. pyogenes, E. coli and K. pneumonia at concentrations of 128 and 64 μg/ml comparable to the activity of the comparison drug norfloxacin. At a concentration of 32 μg/ml, the studied derivative is highly active against S. aureus and S. pyogenes and shows average activity against E. coli and K. pneumonia. The compound VMA–13–06 in dilution from 16 to 4 μg/ml is moderately active against the above-mentioned microorganisms. At concentrations from 2 to 0.25 μg/ml, the pyrimidine derivative is inactive against S. aureus, S. pyogenes, E. coli and K. pneumonia, in all dilutions – against C. freundii and A. baumannii. Conclusions. The results of a screening study indicate a pronounced bactericidal effect of VMA–13–06 against S. aureus, S. pyogenes, E. coli и K. pneumonia comparable to the comparison drug norfloxacin