Magnetic anisotropy in strained manganite films and bicrystal junctions

Transport and magnetic properties of LSMO manganite thin films and bicrystal junctions were investigated. Manganite films were epitaxially grown on STO, LAO, NGO and LSAT substrates and their magnetic anisotropy were determined by two techniques of magnetic resonance spectroscopy. Compare with cubic substrates a small (about 0.3 persentage), the anisotropy of the orthorhombic NGO substrate leads to a uniaxial anisotropy of the magnetic properties of the films in the plane of the substrate. Samples with different tilt of crystallographic basal planes of manganite as well as bicrystal junctions with rotation of the crystallographic axes (RB - junction) and with tilting of basal planes (TB - junction) were investigated. It was found that on vicinal NGO substrates the value of magnetic anisotropy could be varied by changing the substrate inclination angle from 0 to 25 degrees. Measurement of magnetic anisotropy of manganite bicrystal junction demonstrated the presence of two ferromagnetically ordered spin subsystems for both types of bicrystal boundaries RB and TB. The magnitude of the magnetoresistance for TB - junctions increased with decreasing temperature and with the misorientation angle even misorientation of easy axes in the parts of junction does not change. Analysis of the voltage dependencies of bicrystal junction conductivity show that the low value of the magnetoresistance for the LSMO bicrystal junctions can be caused by two scattering mechanisms with the spin- flip of spin - polarized carriers due to the strong electron - electron interactions in a disordered layer at the bicrystal boundary at low temperatures and the spin-flip by anti ferromagnetic magnons at high temperatures.Comment: 26 pages, 10 figure

Symmetry adapted ro-vibrational basis functions for variational nuclear motion calculations: TROVE approach

We present a general, numerically motivated approach to the construction of symmetry adapted basis functions for solving ro-vibrational Schr\"{o}dinger equations. The approach is based on the property of the Hamiltonian operator to commute with the complete set of symmetry operators and hence to reflect the symmetry of the system. The symmetry adapted ro-vibrational basis set is constructed numerically by solving a set of reduced vibrational eigenvalue problems. In order to assign the irreducible representations associated with these eigenfunctions, their symmetry properties are probed on a grid of molecular geometries with the corresponding symmetry operations. The transformation matrices are re-constructed by solving over-determined systems of linear equations related to the transformation properties of the corresponding wavefunctions on the grid. Our method is implemented in the variational approach TROVE and has been successfully applied to a number of problems covering the most important molecular symmetry groups. Several examples are used to illustrate the procedure, which can be easily applied to different types of coordinates, basis sets, and molecular systems

Polaron physics and crossover transition in magnetite probed by pressure-dependent infrared spectroscopy

The optical properties of magnetite at room temperature were studied by infrared reflectivity measurements as a function of pressure up to 8 GPa. The optical conductivity spectrum consists of a Drude term, two sharp phonon modes, a far-infrared band at around 600 cm$^{-1}$, and a pronounced mid-infrared absorption band. With increasing pressure both absorption bands shift to lower frequencies and the phonon modes harden in a linear fashion. Based on the shape of the MIR band, the temperature dependence of the dc transport data, and the occurrence of the far-infrared band in the optical conductivity spectrum the polaronic coupling strength in magnetite at room temperature should be classified as intermediate. For the lower-energy phonon mode an abrupt increase of the linear pressure coefficient occurs at around 6 GPa, which could be attributed to minor alterations of the charge distribution among the different Fe sites.Comment: 7 pages, 7 figure

Объем и размеры пор в первичных агрегатах технического углерода как факторы, влияющие на электрические характеристики вулканизатов

Methods of porous volume in the primary unit of technical carbon are considered. Is established that intramodular space is accessible to rubber macromolecules. Influence of porous volume on electric characteristics is shownВ представленной работе рассмотрены методы определения объема пор в первичном агрегате технического углерода Установлено, что внутриагрегатное пространство доступно для макромолекул каучука. Показано влияние объема пор на электрические характеристики

Retention of knowledge on blood pressure measurement among medical students within preparation for primary accreditation

Aim. To assess the retained knowledge of sixth year medical students on noninvasive blood pressure (BP) measurement.Material and methods. The study included 148 6th year medical students. According to the curriculum, in the fall semester, students studied the procedure of BP measurement according to checklists developed based on ROSOMED. In the spring semester, as part of the preparation course for accreditation, the retained knowledge of students was assessed. A completed skill was assessed at 1 point, not completed — 0 points. Thus, each student can score a maximum of 50 points. The teacher assessed the manipulations during their performing by filling in the checklist items for each student.Results. None of the students completed the full range of manipulations. The number of completed skills ranged from 15 (30%) to 49 (98%) and averaged 33 points on the checklist (66%). In addition, 74% of students (n=109) completed more than half of the required skills. Almost the only item completed by all students (99%, n=146) was a greeting, which was comparable with self-presentation (92%, n=136) and identification of a patient’s personal data (surname and first names) (80%, n=118). The rest of checklist items was performed in the range from 39% (n=57) for “remeasurement of BP on the other hand” to 87% (n=129) for “finding a radial pulse”. Thus, the average fulfillment rate was 67% (n=99). There were following most common mistakes in BP measurement: 39% of students did not measure a patient’s upper arm diameter and did not select the cuff size; every second student (51%) placed the phonendoscope diaphragm under the cuff; 40% of students reduced the cuff pressure with inadequate rate.Conclusion. The retention of knowledge on measuring BP within six months after a detailed analysis and passing a test remains insufficient, but comparable with foreign studies. The data obtained indicate the need for additional trainings both using simulators and in conditions closer to real ones, including with simulated patients

Molecular tectonics: Dimensionality and geometry control of silver coordination networks based on pyrazolyl appended thiacalixarenes

© The Royal Society of Chemistry 2016.Combinations of six new coordinating tectons (3-8) tetrakis-pyrazolyl appended calix[4]arenes, blocked in 1,3-A conformation, based on 1 (tetrathiacalix[4]arene) and 2 (tetrathiatetramercaptocalix[4]arene) derivatives, with AgX salts (X = NO3-, BF4-, XF6- (X = P, As and Sb)) lead to nine new silver coordination networks. The flexible nature of tectons 3-8 (length of the spacer between the macrocycle and the pyrazolyl coordinating unit), their high number of potential coordinating sites and the loose coordination demand of Ag+ cation lead to the formation of a large variety of networks with different dimensionality: from 1D (5-AgSbF6, 5-AgBF4, 7-AgSbF6 and 8-AgNO3) to extended 2D (6-AgBF4 and 8-AgSbF6) and to a series of three isostructural porous diamond-like 3D architectures (6-AgXF6 (X = P, As and Sb))

Vibrational energies of PH3 calculated variationally at the complete basis set limit

The potential energy surface for the electronic ground state of PH3 was calculated at the CCSD(T) level using aug-cc-pV(Q+d)Z and aug-cc-pVQZ basis sets for P and H, respectively, with scalar relativistic corrections included. A parametrized function was fitted through these ab initio points, and one parameter of this function was empirically adjusted. This analytical PES was employed in variational calculations of vibrational energies with the newly developed program TROVE. The convergence of the calculated vibrational energies with increasing vibrational basis set size was improved by means of an extrapolation scheme analogous to the complete basis set limit schemes used in ab initio electronic structure calculations. The resulting theoretical energy values are in excellent agreement with the available experimentally derived values

Droplet-like Fermi surfaces in the anti-ferromagnetic phase of EuFe2_2As2_2, an Fe-pnictide superconductor parent compound

Using angle resolved photoemission it is shown that the low lying electronic states of the iron pnictide parent compound EuFe$_2$As$_2$ are strongly modified in the magnetically ordered, low temperature, orthorhombic state compared to the tetragonal, paramagnetic case above the spin density wave transition temperature. Back-folded bands, reflected in the orthorhombic/ anti-ferromagnetic Brillouin zone boundary hybridize strongly with the non-folded states, leading to the opening of energy gaps. As a direct consequence, the large Fermi surfaces of the tetragonal phase fragment, the low temperature Fermi surface being comprised of small droplets, built up of electron and hole-like sections. These high resolution ARPES data are therefore in keeping with quantum oscillation and optical data from other undoped pnictide parent compounds.Comment: 4 figures, 6 page

Взаимосвязь предельного напряжения сдвига в модельных дисперсиях технического углерода с показателями резиновых смесей и резин

The influence of morphological characteristics of carbon black on the critical shear stress in its model dispersions in dibutyl phthalate was established. The possibility of forecasting the properties of a number of rubber mixtures and rubbers by means of the critical shear stress was shown.Установлено влияние морфологических характеристик технического углерода на предельное напряжение сдвига в его модельных дисперсиях в дибутилфталате. Показана возможность прогнозирования ряда свойств резиновых смесей и резин с помощью показателя предельного напряжения сдвига