Weak ferromagnetism and short range polar order in NaMnF 3 thin films

The orthorhombically distorted perovskite NaMnF3 has been predicted to become ferroelectric if an a = c distortion of the bulk Pnma structure is imposed. In order to test this prediction, NaMnF3 thin films were grown on SrTiO3 (001) single crystal substrates via molecular beam epitaxy. The best films were smooth and single phase with four different twin domains. In-plane magnetization measurements revealed the presence of antiferromagnetic ordering with weak ferromagnetism below the Néel temperature TN = 66 K. For the dielectric studies, NaMnF3 films were grown on a 30 nm SrRuO3 (001) layer used as a bottom electrode grown via pulsed laser deposition. The complex permittivity as a function of frequency indicated a strong Debye-like relaxation contribution characterized by a distribution of relaxation times. A power-law divergence of the characteristic relaxation time revealed an order-disorder phase transition at 8 K. The slow relaxation dynamics indicated the formation of super-dipoles (superparaelectric moments) that extend over several unit cells, similar to polar nanoregions of relaxor ferroelectrics

1-Methyl-2,3-dihydro-1H-benzimidazole-2-selone

The title compound C8H8N2Se, is the product of the reaction of 2-chloro-1-methyl­benzimidazole with sodium hydro­selenide. The mol­ecule is almost planar (r.m.s. deviation = 0.041 Å) owing to the presence of the long chain of conjugated bonds (Se=C—NMe—C=C—C=C—C=C—NH). The C=Se bond length [1.838 (2) Å] corresponds well to those found in the close analogs and indicates its pronounced double-bond character. In the crystal, mol­ecules form helicoidal chains along the b axis by means of N—H⋯Se hydrogen bonds

Integrable quadratic Hamiltonians on so(4) and so(3,1)

We investigate a special class of quadratic Hamiltonians on so(4) and so(3,1) and describe Hamiltonians that have additional polynomial integrals. One of the main results is a new integrable case with an integral of sixth degree.Comment: 16 page

Plasma immersion ion implantation for surface treatment of complex branched structures

The paper presents experimental results demonstrating the capabilities of plasma immersion ion implantation of silicon (Si) for surface treatment of complex branched structures such are self-expanding intravascular nickel-titanium (NiTi) stents. Using NiTi stents of diameter 4 and 8 mm, it is shown that plasma immersion ion implantation can provide rather homogeneous doping of their outer and inner surfaces with Si atoms. Also presented are research data on the processes that determine the thickness, composition, and structure of surface layers subjected to this type of treatment

The study of spectral changes in THz range in normal and pathological skin in vivo depending on the dehydration methods used

The terahertz (THz) attenuated total reflectance (ATR) imaging of normal and pathological skin under the action of various dehydration agents was carried out in vivo. Studies were conducted on animal models (the mouse), patients with diabetes, and healthy volunteers. For measurements, each animal was leaned against the ATR prism of the skin surface, and several locations in the skin of each animal were analyzed. Places on the skin for analysis were chosen so that the intensity spectra of the THz signal were practically the same for selected points. THz spectra measurements were carried out every 10 minutes within 45 minutes interval under the action of a dehydration agent. 40% glucose was shown to provide the most effective improving tissue optical clearing effect in the THz range

1,3-Benzothia­zole-2(3H)-selone

The title compound, C7H5NSSe, is the product of the reaction of 2-chloro­benzothia­zole with sodium hydro­selenide. The mol­ecule is almost planar (r.m.s. deviation = 0.018 Å) owing to the presence of the long chain of conjugated bonds (Se=C—N—C=C—C=C—C=C). The geometrical parameters correspond well to those of the analog N-methyl­benzothia­zole-2(3H)-selone, demonstrating that the S atom does not take a significant role in the electron delocalization within the mol­ecule. In the crystal, mol­ecules form centrosymmetric dimers by means of inter­molecular N—H⋯Se hydrogen bonds. The dimers have a nonplanar ladder-like structure. Furthermore, the dimers are linked into ribbons propagating in [010] by weak attractive Se⋯S [3.7593 (4) Å] inter­actions

Creation of a magnetic driven gate for THz rays

In this paper, magnetic fluids based on iron oxide Fe3O4 and 5BDSR alloy were obtained. Magnetic particles were obtained by nanosecond pulsed laser ablation. The preparation of the magnetic fluid was carried out by mechanical and ultrasonic stirring in a solution of polymethylphenylsiloxane. It is shown that under the influence of an external magnetic field, the spectral properties of the magnetic fluid of the 5BDSR alloy correspond to characteristics that can be used to create a magnetic gate

Inter-calibration of Infrared Channels of Geostationary Meteorological Satellite Imagers

This article examines a method of inter-calibration for MSU-GS imager of the Russian Geostationary Earth Orbit (GEO) satellite Elektro-L No. 2. Since the launch (December 11, 2015), the satellite's radiation cooler has been operating in an abnormal mode, so the calibration of the IR channels of the MSU-GS imager differed from that pre-flight and, in general, could have a daily variability. To ensure the satellite's further operation in orbit, it was necessary to calibrate imager channels at a frequency that would allow to identify daily calibration course to detect and compensate its sources. In order to do this, we have developed a special method of GEO-GEO inter-calibration. The calibration of MSU-GS was performed using SEVIRI imager installed on the GEO satellite Meteosat-10. SEVIRI was chosen as a reference instrument because its spectral channels are similar to those of MSU-GS. The MSU-GS was calibrated according to the regressions calculated from the simultaneous images of the field of regard selected between the sub-satellite points. The dynamic brightness temperature range was determined by deep convective clouds in high troposphere and warm ocean surface. Using the proposed method of inter-calibration, it was possible to confirm the absence of a significant daily variation of the calibration since November 2017. The amplitude of the variation smoothly increases from ~0.2 K at high (~300 K) BTs to ~1.0 K when the brightness temperature decreased to 200 K. These estimates allow the use of the Fourier spectrometer IKFS-2 installed on the Russian Low-Earth-Orbit (LEO) satellite Meteor-M No. 2 to verify the developed GEO-GEO scheme of inter-calibration. Despite the specifics of the situation on board Elektro-L No. 2, the proposed method of GEO-GEO inter-calibration can be applied to radiometers of other neighboring satellites that differ in SSP and spatial resolution