Emergent Berezinskii-Kosterlitz-Thouless Phase in Low-Dimensional Ferroelectrics.

Using first-principles-based simulations merging an effective Hamiltonian scheme with scaling, symmetry, and topological arguments, we find that an overlooked Berezinskii-Kosterlitz-Thouless (BKT) phase sustained by quasicontinuous symmetry emerges between the ferroelectric phase and the paraelectric one of BaTiO_{3} ultrathin film, being under tensile strain. Not only do these results provide an extension of BKT physics to the field of ferroelectrics, but they also unveil their nontrivial critical behavior in low dimensions.

Topological Point Defects in Relaxor Ferroelectrics.

First-principles-based effective Hamiltonian simulations are used to reveal the hidden connection between topological defects (hedgehogs and antihedgehogs) and relaxor behavior. Such defects are discovered to predominantly lie at the border of polar nanoregions in both Ba(Zr_{0.5}Ti_{0.5})O_{3} (BZT) and Pb(Sc_{0.5}Nb_{0.5})O_{3} (PSN) systems, and the temperature dependency of their density allows us to distinguish between noncanonical (PSN) and canonical (BZT) relaxor behaviors (via the presence or absence of a crossing of a percolation threshold). This density also possesses an inflection point at precisely the temperature for which the dielectric response peaks. Moreover, hedgehogs and antihedgehogs are found to be mobile excitations, and the dynamical nature of their annihilation is demonstrated (using simple hydrodynamical arguments) to follows laws, such as those of Vogel-Fulcher and Arrhenius, that are characteristic of dipolar relaxation kinetics of relaxor ferroelectrics.

Pulsed corona discharge: the role of ozone and hydroxyl radical in aqueous pollutants oxidation.

Ozone and hydroxyl radical are the most active oxidizing species in water treated with gas-phase pulsed corona discharge (PCD). The ratio of the species dependent on the gas phase composition and treated water contact surface was the objective for the experimental research undertaken for aqueous phenol (fast reaction) and oxalic acid (slow reaction) solutions. The experiments were carried out in the reactor, where aqueous solutions showered between electrodes were treated with 100-ns pulses of 20 kV voltage and 400 A current amplitude. The role of ozone increased with increasing oxygen concentration and the oxidation reaction rate. The PCD treatment showed energy efficiency surpassing that of conventional ozonation.

[Low-temperature sterilization for the surgical infection prophylaxis].

The comparative characteristic of the accepted methods of low-temperature sterilization of medical equipment is given. Special attention is devoted to the surgical infection prophylaxis. The efficacy, expediency and safety of gas sterilization with ethilenoxide is proved. Plasmic methods of sterilization is recommended for use together with other methods of low-temperature sterilization.

Discovery of stable skyrmionic state in ferroelectric nanocomposites.

Non-coplanar swirling field textures, or skyrmions, are now widely recognized as objects of both fundamental interest and technological relevance. So far, skyrmions were amply investigated in magnets, where due to the presence of chiral interactions, these topological objects were found to be intrinsically stabilized. Ferroelectrics on the other hand, lacking such chiral interactions, were somewhat left aside in this quest. Here we demonstrate, via the use of a first-principles-based framework, that skyrmionic configuration of polarization can be extrinsically stabilized in ferroelectric nanocomposites. The interplay between the considered confined geometry and the dipolar interaction underlying the ferroelectric phase instability induces skyrmionic configurations. The topological structure of the obtained electrical skyrmion can be mapped onto the topology of domain-wall junctions. Furthermore, the stabilized electrical skyrmion can be as small as a few nanometers, thus revealing prospective skyrmion-based applications of ferroelectric nanocomposites.

[Reliability of the sterilization of surgical instruments is a key point in prevention of surgical infection]. / Nadezhnost' sterilizatsii izdelii meditsinskogo naznacheniia.

Occurrence of postoperative purulent-inflammative complications (PPIC), their structure and dynamics after improvement of sterilization are studied. For epidemiological analysis 65,246 medical histories of operated patients were studied, in 404 of them PPIC were revealed. The PPIC rate reduced from 3.05% in 1981 to 0.49 in 2000 though surgical activity increased 12 times after this period. Thus developed measures for improvement of sterilization promoted reduction of the PPIC rate.

Control of vortices by homogeneous fields in asymmetric ferroelectric and ferromagnetic rings.

Effective Hamiltonians have been used (i) to demonstrate that the shape asymmetry of ferromagnetic rings is essential to the recently discovered switching of the chirality of their vortices by homogeneous magnetic fields, via a transition into onion states; (ii) to reveal that an electric vortex can also be controlled by a homogeneous electric field in asymmetric ferroelectric nanorings, via the formation of antiferrotoroidic pair states rather than onion states; and (iii) to provide the fundamental reason that allows such control, namely, two new interaction energies involving a vector characterizing the asymmetry, the applied field, and the toroidal moment.

High-pressure effect on PbTiO3: an investigation by Raman and x-ray scattering up to 63 GPa.

We report a room-temperature high-pressure x-ray and Raman scattering investigation of lead titanate (PbTiO3) up to 63 GPa. Three continuous phase transitions at 13, 20, and 45 GPa between tetragonal-like phases occur. As a result, no evidence is found for a pressure-induced morphotropic phase boundary. Our study provides experimental evidence that PbTiO3 presents a complex sequence of phases accommodating pressure through mechanisms involving oxygen octahedra tilting and reentrance of ferroelectricity.

Controlling toroidal moment by means of an inhomogeneous static field: an ab initio study.

A first-principles-based approach is used to show (i) that stress-free ferroelectric nanodots under open-circuit-like electrical boundary conditions maintain a vortex structure for their local dipoles when subject to a transverse inhomogeneous static electric field, and, more importantly, (ii) that such a field leads to the solution of a fundamental and technological challenge: namely, the efficient control of the direction of the macroscopic toroidal moment. The effects responsible for such striking features are revealed and discussed.

Electric-field-induced domain evolution in ferroelectric ultrathin films.

The electric-field-induced evolution of the recently discovered periodic 180 degree nanostripe domain structure is predicted in epitaxial Pb(Zr0.5Ti0.5)O3 ultrathin films from first principles. This evolution involves (1) the lateral growth of majority dipole domains at the expense of minority domains with the overall stripe periodicity remaining unchanged, (2) the creation of surface-avoiding nanobubbles, and (3) the formation of a single monodomain state. Analogies and differences (i) with ferroelectric thin films made of BaTiO3 and (ii) with ferromagnetic thin films under magnetic field are discussed.

The demogeographic region as an object for planning and management.

PIP: A basic task in population geography is to investigate the spatial aspects of Soviet population policy. The concept of a demogeographic region is proposed as an approach for planning and managing demographic processes. A demogeographic region is an area with a certain combination of conditions and factors affecting demographic processes in order to endow it with distinctive tendencies in the evolution of demographic processes and structures and, as a result, with a given type of demographic indications. A demogeographic regionalization should be considered as a particular type of general economic regionalization. A method of identifying demogeographic regions with particular reference to the region Sverdlovsk Oblast has been worked out. It involves several steps. A preparatory stage involves the study of the territorial characteristics of urbanization in the oblast and the use of the field potential technique to identify areas with different levels of urbanization. The field potential of settlement makes it possible to establish spatial concentrations of population and the gravitation of places within the field of settlement, which are the basic features of contemporary urbanization. The number of minor civil divisions of Sverdlovsk Oblast was classified on the basis of demographic characteristics reflecting population change, age and sex structure, natural increase, and migration. The pattern recognition method, which makes it possible to combine into classes those elements that come closest to each other in terms of a series of attributes, was used. The entire set of minor civil divisions in Sverdlovsk Oblast was divided into 4 classes that differed in the quantitative parameters of demographic characteristics. These classes happen to have a fairly compact distribution within the oblast so that these classes could also be treated as territorial types of demographic setting. The plotting of these types on a map of the field potential of settlement yielded 3 demographic regions within the oblast: a Central Region with a high level of urbanization and steady population growth; a Peripheral Region with a low level of urbanization and a pronounced population decline; and a Transition Region with a medium level of urbanization, broken down into 2 subregions A (with stable population) and B (with declining population). The spatial and functional linkages between urbanization and demographic processes that can be identified within demogeographic regions suggest that any modification of some processes will affect others. This is crucial for controlling the spatial development of urbanization and demographic processes. Consequently, the demographic setting within Sverdlovsk Oblast can be optimized by controlling the demographic development within demographic regions. That proposition is illustrated with some examples.^ieng