Semiclassical dynamics of domain walls in the one-dimensional Ising ferromagnet in a transverse field

We investigate analytically and numerically the dynamics of domain walls in a spin chain with ferromagnetic Ising interaction and subject to an external magnetic field perpendicular to the easy magnetization axis (transverse field Ising model). The analytical results obtained within the continuum approximation and numerical simulations performed for discrete classical model are used to analyze the quantum properties of domain walls using the semiclassical approximation. We show that the domain wall spectrum shows a band structure consisting of 2$S$ non-intersecting zones.Comment: 15 pages, 9 figure

Synthesis, structure, and biologic activity of products of reactions between dinitrodichlorobenzofuroxane and aminopyrimidines in aqueous dimethyl sulfoxide

© 2016, Pleiades Publishing, Ltd.Reactions of 4,6-dinitro-5,7-dichlorobenzofuroxane with substituted pyrimidines in aqueous DMSO proceed through an intermediate formation of 5-hydroxy-4,6-dinitro-7-chlorobenzofuroxane owing to the hydrolysis of one of the chlorine atoms with the subsequent formation of pyrimidine salts exhibiting a high biologic action

Stable topological textures in a classical 2D Heisenberg model

We show that stable localized topological soliton textures (skyrmions) with $\pi_2$ topological charge $\nu \geq 1$ exist in a classical 2D Heisenberg model of a ferromagnet with uniaxial anisotropy. For this model the soliton exist only if the number of bound magnons exceeds some threshold value $N_{\rm cr}$ depending on $\nu$ and the effective anisotropy constant $K_{\rm eff}$. We define soliton phase diagram as the dependence of threshold energies and bound magnons number on anisotropy constant. The phase boundary lines are monotonous for both $\nu=1$ and $\nu >2$, while the solitons with $\nu=2$ reveal peculiar nonmonotonous behavior, determining the transition regime from low to high topological charges. In particular, the soliton energy per topological charge (topological energy density) achieves a minimum neither for $\nu=1$ nor high charges, but rather for intermediate values $\nu=2$ or $\nu=3$.Comment: 8 pages, 4 figure

Antibacterial and photochemical properties of cellulose nanofiber-titania nanocomposites loaded with two different types of antibiotic medicines

Nanocomposite dermal drug delivery systems based on cellulose nanofibers with grafted titania nanoparticles loaded by two antibiotic medicines from different classes, i.e. tetracycline (TC) and phosphomycin (Phos), were successfully produced by a ‘‘green chemistry’’ approach in aqueous media. The influence of a different surface binding mechanism between the drug molecule and modified cellulose nanofibers on the release of the drug and, as a result, on antimicrobial properties against common pathogens Gram-positive, Staphylococcus aureus and Gram-negative Escherichia coli was investigated. The disk diffusion method and broth culture tests using varying concentrations of drugs loaded to nanocomposites were carried out to investigate the antibacterial effects. The influence of UV irradiation on the stability of the obtained nanocomposites and their antibacterial properties after irradiation were also investigated, showing enhanced stability especially for the TC loaded materials. These findings suggest that the obtained nanocomposites are promising materials for the development of potentially useful antimicrobial patches

Magnetic vortex as a ground state for micron-scale antiferromagnetic samples

Here we consider micron-sized samples with any axisymmetric body shape and made with a canted antiferromagnet, like hematite or iron borate. We find that its ground state can be a magnetic vortex with a topologically non-trivial distribution of the sublattice magnetization $\vec{l}$ and planar coreless vortex-like structure for the net magnetization $\vec{M}$. For antiferromagnetic samples in the vortex state, in addition to low-frequency modes, we find high-frequency modes with frequencies over the range of hundreds of gigahertz, including a mode localized in a region of radius $\sim$ 30--40 nm near the vortex core.Comment: 20 pages, 1 figur

The local crystallization in nanoscale diamond-like carbon films during annealing

The local crystallization during annealing at 600° C in nanoscale diamond-like carbon coatings films grown by pulsed vacuum-arc deposition method was observed using modern techniques of high-resolution transmission electron microscopy. The crystallites formed by annealing have a face-centred cubic crystal structure and grow in the direction [011] as a normal to the film surface. The number and size of the crystallites depend on the initial values of the intrinsic stresses before annealing, which in turn depend on the conditions of film growth. The sizes of crystallites are 10 nm for films with initial compressive stresses of 3 GPa and 17 nm for films with initial compres- sive stresses of 12 GPa. Areas of local crystallization arising during annealing have a structure dif- ferent from the graphit

Novel biomimetic systems based on polyethylene glycols and amphiphilic phosphonium salt. Self-organization and solubilization of hydrophobic guest

The solution behavior of single and binary systems based on biorelevant building blocks, i.e., polyethylene glycol (PEG) of different molecular weight, and a cationic surfactant, cetyltriphenylphosphonium bromide (TPPB), has been studied. Tensiometry data for PEG-water solutions provide critical aggregation concentrations which decrease with an increase of molecular weight of the polymer. Large particles of ≥200 nm occur in the PEG-1000 solution along with the smaller ones, while in the PEG-400 and PEG-20000 samples only populations coinciding with the size of the polymer coils are found. The dye solubilization study reveals that some hydrophobic domains occur in the PEG solution. The binary PEG-TPPB systems demonstrate a synergetic behavior, i.e. a decrease in critical micelle concentration and much higher solubilization power as compared to single TPPB micelles. The data obtained reveal that PEG-TPPB assemblies present soft nanocontainers, which (i) are composed of biorelevant components; (ii) are formed at low concentrations; (iii) are characterized by nanoscale dimension; (iv) exhibit high binding capacity toward water insoluble guest. Based on these features they may be considered as candidates for the drug delivery formulations. © 2013 Elsevier Ltd. All rights reserved

Autoimmune polyglandular syndrome type I. Features of clinical manifestations, difficulties in diagnosis and methods of correction

Autoimmune polyglandular syndrome (APG) type I is an orphan disease with autosomal recessive inheritance caused by mutations in the autoimmune regulator gene (AIRE); the disease onset typically occurs in childhood. The disease is characterized by a wide variety of clinical manifestations with a certain stage in the manifestation of individual symptoms. The rare occurrence of this pathology determines its late diagnosis, which can lead to the decompensated life-threatening conditions and an unfavorable outcome. Widely informing pediatric specialists will contribute to the development of a diagnostic algorithm for timely verifying the disease from the moment its first clinical manifestations appear, and will improve the quality and life expectancy of the patients

Tomographic Separation of Composite Spectra. VIII. The Physical Properties of the Massive Compact Binary in the Triple Star System HD 36486 (delta Orionis A)

Double-lined spectroscopic orbital elements have recently been found for the central binary in the massive triple, delta Orionis A based on radial velocities from cross-correlation techniques applied to IUE high dispersion spectra and He I 6678 spectra obtained at Kitt Peak. The primary and secondary velocity amplitudes were found to be 94.9 +/- 0.6 km/s and 186 +/- 9 km/s respectively. Tomographic reconstructions of the primary and secondary stars' spectra confirm the O9.5 II classification of the primary and indicate a B0.5 III type for the secondary. The widths of the UV cross-correlation functions are used to estimate the projected rotational velocities, Vsin i = 157 +/- 6 km/s and 138 +/- 16 km/s for the primary and secondary, respectively implying that both stars rotate faster than their orbital motion. We used the spectroscopic results to make a constrained fit of the Hipparcos light curve of this eclipsing binary, and the model fits limit the inclination to the range between 67 and 77 degrees. The i = 67 degrees solution, which corresponds to a near Roche-filling configuration, results in a primary mass of 11.2 solar masses and a secondary mass of 5.6 solar masses, both of which are substantially below the expected masses for stars of their luminosity. This binary may have experienced a mass ratio reversal caused by Case A Roche lobe overflow, or the system may have suffered extensive mass loss through a binary interaction, perhaps during a common envelope phase, in which most of the primary's mass was lost from the system rather than transferred to the secondary.Comment: 27 pages, 15 figures in press, the Astrophysical Journal, February 1, 200