Comparison of superconductivity in Sr_2RuO_4 and copper oxides

To compare the superconductivity in strongly correlated electron systems with the antiferromagnetic fluctuations in the copper oxides and with the ferromagnetic fluctuations in Sr_2RuO_4 a t-J-I model is proposed. The antiferromagnetic coupling J results in the superconducting state of d_{x^2-y^2} symmetry and the ferromagnetic coupling constant I results in the spin-triplet p-type state. The difference in the gap anisotropies provides the large difference in T_c values, for the typical values of the coupling constants: T_c of order of 1K for the ruthenate and T_c of order of 100K for the cuprates.Comment: 4 pages, RevTEX, 3 figs. Submitted to Phys. Rev. Let

Spin state crossover in Co3BO5

We have investigated the spin and oxidation states of Co in Co3BO5 using x-ray magnetic circular dichroism (XMCD) and dc magnetic susceptibility measurements. At low temperatures, XMCD experiments have been performed at the Co K-edge in Co3BO5 and Co2FeBO5 single crystals in the fully ferrimagnetically ordered phase. The Co (K-edge) XMCD signal is found to be related to the Co2+ magnetic sublattices in both compounds, providing strong experimental support for the low-spin (LS) Co3+ scenario. The paramagnetic susceptibility is highly anisotropic. An estimation of the effective magnetic moment in the temperature range 100-250 K correlates well with two Co2+ ions in the high-spin (HS) state and some orbital contribution, while Co3+ remains in the LS state. The crystal structure of the Co3BO5 single crystal has been solved in detail at the T range 296-703 K. The unit cell parameters and volume show anomalies at 500 and 700 K. The octahedral environment of the Co4 site strongly changes with heating. The generalized gradient approximation with Hubbard U correction calculations have revealed that, at low-temperatures, the system is insulating with a band gap of 1.4 eV, and the Co2+ ions are in the HS state, while Co3+ are in the LS state. At high temperatures (T > 700 K), the charge ordering disappears, and the system becomes metallic with all Co ions in 3d7 electronic configuration and HS state. © 2021 American Physical Society

In Situ Spectral Magnetoellipsometry for Structural, Magnetic and Optical Properties of Me/Si (Me Mn, Fe) Nanolayers

In our work we present in-situ spectral magnetoellipsometer is equipped with sapphire manipulator. which allows us to carry out in-situ and in-time optical and magnetooptical measurements in the range from 10 K to 1500 K in spectral range 1.5 eV-4.0 eV (830 nm-300 nm), the range of magnetic fields is +/-0.4 T. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3555

Tunneling of quantum rotobreathers

We analyze the quantum properties of a system consisting of two nonlinearly coupled pendula. This non-integrable system exhibits two different symmetries: a permutational symmetry (permutation of the pendula) and another one related to the reversal of the total momentum of the system. Each of these symmetries is responsible for the existence of two kinds of quasi-degenerated states. At sufficiently high energy, pairs of symmetry-related states glue together to form quadruplets. We show that, starting from the anti-continuous limit, particular quadruplets allow us to construct quantum states whose properties are very similar to those of classical rotobreathers. By diagonalizing numerically the quantum Hamiltonian, we investigate their properties and show that such states are able to store the main part of the total energy on one of the pendula. Contrary to the classical situation, the coupling between pendula necessarily introduces a periodic exchange of energy between them with a frequency which is proportional to the energy splitting between quasi-degenerated states related to the permutation symmetry. This splitting may remain very small as the coupling strength increases and is a decreasing function of the pair energy. The energy may be therefore stored in one pendulum during a time period very long as compared to the inverse of the internal rotobreather frequency.Comment: 20 pages, 11 figures, REVTeX4 styl

Comparative use efficiency of the same type feed additives in the diet of replacement stock and laying hens of the parent herd

The use of two similar feed additives Sorbitox and Probitox in the diet of replacement stock and subsequently in the diet of laying hens, at a dose of 0.50 kg/t of feed allowed to increase the poultry survival rate at 18 weeks of age by 1.4% with the addition of Sorbitox and 6.4% - with Probitox, the group uniformity by 5.3 and 7.3%, respectively, in comparison with the control group. At the same time, the culling of birds in the experimental groups decreased due to endoenteritis and necrotic enteritidis, and the antibody titer to Gumboro disease increased in the blood. During the productive period of laying hens, the difference in the antibody titer was significantly higher, as was the livestock survival rate. The tested feed additives contributed to a better development of ovogenesis organs. As a result, the egg productivity of chickens with Sorbitox was higher than the control group by 6.5%, with Probitox – by 11.6%. The study of the egg incubation qualities showed that the young stock hatching rate from an average egg size in the group with Sorbitox was 6.9% higher than the control group, with Probitox – by 11.0%, and the hatchability of eggs was 1.1 and 1.6% higher than in the average one. In laying hens at the beginning and at the end of egg laying, the number of infertile small eggs decreased in the group with Sorbitox by 0.60%, with Probitox - by 1.0%, large eggs – by 1.23 and 2.45%, respectively. The chicken hatching rate from small and large eggs in poultry of the experimental groups exceeded the control by 2.9-5.9% at the beginning of egg laying, by 10.0-14.8% at its completion at the age of 56 weeks. The addition of Sorbitox in the diet of replacement stock allowed to reduce feed costs for growing one head of service pullet by 6.9%, with Probitox – by 12.6%, to increase the production profitability by 5.5 and 7.8%, and in laying hens of experimental groups, feed costs decreased by 4.4 and 10.0%, profitability increased by 2.0 and 5.3%, respectively

Femtosecond laser FLEx surgery — first experience of application

ABSTRACT Purpose. A comparative estimation of the thickness of corneal flap formed with Moria microkeratome and VisuMax femtosecond laser as well as refraction, visual acuity, changes of contrast sensitivity and higher order aberrations after LASIK and FLEx for myopia and myopic astigmatism correction. Material and methods. Two groups of patients, 70 eyes in each were investigated. In the group 1 the standard LASIK was performed. In the group 2 the FLEx was carried out. Besides standard investigations, in both groups wavefront aberrations were measured before operation and 1 month later in Malacara notation with WASCA aberrometer (Carl Zeiss Meditec, Germany) with a non-medicamentous pupil diameter of 6mm. Flap thickness measurement in the center of the cornea and 1, 2 and 3mm from the center was performed in both groups with the Visante OCT (Carl Zeiss Meditec) in High Resolution Corneal Quad and High Resolution Corneal Single modes. Contrast sensitivity was measured in both groups with CSV-1000 unit (VECTORVISION). Follow-up period was 1 month. Results. Uncorrected visual acuity before surgery in groups 1 and 2 was 0.05±0.07; 0.06±0.02 and made after the operation 0.99±0.05; 0.95±0.09 (p>0.05). Spheric equivalent before surgery in groups 1 and 2 was -4.13±2.08 D; -3.78±1.47 D and after surgery became 0.02±0.16 D; 0.03±0.14 D (p>0.05). Corrected visual acuity before surgery in groups 1 and 2 was 0.98±0.05; 0.99±0.02 and made 0.99±0.07; 0.98±0.04 after surgery (p>0.05). The RMS HO before surgery in groups 1 and 2 was 0.18±0.07 µm, 0.17±0.09 µm and increased after surgery up to 0.37±0.11 µm, 0.29±0.07 µm (p<0.05). Spheric aberration value in groups 1 and 2 before surgery was -0.12±0.19 µm; -0.11±0.15 µm, after surgery it increased negatively in both groups up to -0.53±0.30 µm; -0.24±0.28 µm (p<0.05). Conclusions. 1. Laser femtosecond microkeratome VisuMax allows FLEx without excimer laser. 2. Laser femtosecond microkeratome VisuMax allows a formation of corneal flaps with precisely preset thickness parameters unlike mechanical microkeratome. 3. FLEx provides an improvement of visual acuity up to preoperative best corrected level with restoration of preoperative contrast sensitivity parameters under mesopic conditions at 1 month after the operation