Anomalous electrical conductivity in rapidly crystallized Cu50−x{}_{50-x}Zrx{}_{x} (x = 50 - 66.6) alloys

Cu${}_{50-x}$Zr${}_{x}$ (x = 50, 54, 60 and 66.6) polycrystalline alloys were prepared by arc-melting. The crystal structure of the ingots has been examined by X-ray diffraction. Non-equilibrium martensitic phases with monoclinic structure were detected in all the alloys except Cu${}_{33.4}$Zr${}_{66.6}$. Temperature dependencies of electrical resistivity in the temperature range of T = 4 - 300 K have been measured as well as room temperature values of Hall coefficients and thermal conductivity. Electrical resistivity demonstrates anomalous behavior. At the temperatures lower than 20 K, their temperature dependencies are non-monotonous with pronounced minima. At elevated temperatures they have sufficiently non-linear character which cannot be described within framework of the standard Bloch--Gr\"{u}neisen model. We propose generalized Bloch--Gr\"{u}neisen model with variable Debye temperature which describes experimental resistivity dependencies with high accuracy. We found that both the electrical resistivity and the Hall coefficients reveal metallic-type conductivity in the Cu-Zr alloys. The estimated values of both the charge carrier mobility and the phonon contribution to thermal and electric conductivity indicate the strong lattice defects and structure disorder.Comment: 6 pages, 3 figure

Properties of the amorphous-nanocrystalline Gd2O3 powder prepared by pulsed electron beam evaporation

An amorphous-nanocrystalline Gd2O3 powder with a specific surface area of 155 m2/g has been prepared using pulsed electron beam evaporation in vacuum. The nanopowder consists of 20- to 500-nm agglomerates formed by crystalline nanoparticles (3-12 nm in diameter) connected by amorphous-nanocrystalline strands. At room temperature, the Gd2O3 nanopowder exhibits a paramagnetic behavior. The phase transformations occurring in the powder have been investigated using differential scanning calorimetry and thermogravimetry (40-1400°C). The amorphous phase of the nanopowder is thermally stable up to a temperature of 1080°C. It has been found that the amorphous phase has an inhibitory effect on the temperature of the polymorphic transformation from the cubic phase into the monoclinic phase. It has been revealed that, compared with the microcrystalline powder, the Gd2O3 nanopowder is characterized by a complete quenching of photoluminescence. © 2013 Pleiades Publishing, Ltd

Evolution of the Crystal and Electronic Structures of the RBa 2 Cu 3 O 6 + δ Cuprates in Annealing

Abstract: The crystal structure and the magnetic properties of the HTSC cuprates YBa 2 Cu 3 O 6 + δ , Y 1 ‒   x Ca x Ba 2 Cu 3 O 6 + δ , and Nd 1 + x Ba 2 – x Cu 3 O 6 + δ (x = 0.2) with the structure of a layered perovskite are studied. The well-known aging effect detected in these HTSC materials during storage under standard conditions, namely, an increase in their critical temperature T c and a decrease in lattice parameter c in time, is investigated. Using YBa 2 Cu 3 O 6 + δ as an example, we show that the dependence of c on the oxygen content undergoes the following changes in time: (1) the negative slope of the dependence with respect to axis δ increases and (2) nonlinearity appears and grows in time according to a quadratic law. The first type of changes is explained by an increase in the valence of copper ions, which is accompanied by a decrease in their radius. The second type is explained by the electrostatic interaction of structural CuO 2 planes due to the accumulation of electron holes, which come from CuO δ planes, in them. The calculation of the second type of changes in parameter c in the YBa 2 Cu 3 O 6 + δ cuprate exhibits good quantitative agreement with the experimental data. The second-type changes in the Y 1 – x Ca x Ba 2 Cu 3 O 6 + δ compound (hole doping of CuO 2 planes) turn out to be identical to those in YBa 2 Cu 3 O 6 + δ . However, the differently directed (in time) changes in lattice parameter c in Nd 1 + x Ba 2 – x Cu 3 O 6 + δ indicate that the CuO 2 planes in the neodymium cuprate are doped by electrons at the initial stage of aging. However, when these planes are saturated with holes in time, the type of doping changes from n to p without a noticeable change in the crystal structure, which has been considered to be impossible for layered cuprates to date. © 2018, Pleiades Publishing, Inc

THE SIZE EFFECT IN MAGNETOCALORIC MANGANITES Nd0.85Me0.15MnO3 (Me=Ca, Sr, Ba)

We modified the magnetic properties of the Nd0.85Me0.15MnO3 manganite by changing the average radius of the ion in the A-position Nd3+→Ca2+,Sr2+,Ba2+.We show that the paramagnetic (PM)-ferromagnetic (FM) transition temperature and the Curie-Weiss temperature change increase with increasig Me2+ radius.Работа выполнена по Государственному заданию ИМЕТ УрО РАН в рамках Программы фундаментальных исследований государственных академий по теме 0369-2019-0001 с использованием оборудования ЦКП «Урал-М»

Cation Nonstichiometry, Crystal Structure, and Magnetic Properties of Eu2-XMnXO3

The features of the formation of crystalline and magnetic subsystems in Eu2-xMnxO3 manganite were studied by X-ray diffraction and magnetometry. The nature of the magnetic ordering has been established, the temperatures of magnetic phase transitions have been determined as a function of the Eu/Mn.Работа выполнена по Государственному заданию ИМЕТ УрО РАН в рамках Программы фундаментальных исследований государственных академий по теме 0369-2019-0001 с использованием оборудования ЦКП «Урал-М»

Фармакоэкономическое исследование различных вариантов лечения тромбофлебита поверхностных вен нижних конечностей

Background. The superficial veins thrombophlebitis (SVT) of lower extremities treatment can include conservative therapy (pharmacotherapy), crossectomy and phlebectomy.  Objective: рharmacoeconomic evaluation of pharmacotherapy, crossectomy (in combination with pharmacotherapy) and phlebectomy (in combination with pharmacotherapy) in patients with SVT of lower extremities.  Material and methods. Pharmacoeconomic evaluation was carried out using cost-effectiveness analysis (CEA) by calculating the costeffectiveness ratio (CER). The relapse/progression of the disease within 3 months after the end of treatment, the dynamics of pain, psychological, physical, social factors and the visual analog scale (VAS) indicator were used as parameters of clinical effectiveness. To assess the reliability of the obtained results, a deterministic, multivariate sensitivity analysis was performed.  Results. Considering part of patients without progression and relapse within 3 months after the end of therapy as an indicator of clinical effectiveness, it was found that median CER for pharmacotherapy (22069,01) was significantly lower than for crossectomy (83353,91) and phlebectomy (95702,96) (p=0,000). Also median CER for crossectomy technique was significantly lower than for phlebectomy (p=0,003). The CER values for the dynamics of pain, psychological, physical, social factors and VAS indicators were significantly lower for pharmacologic treatment than for crossectomy and phlebectomy. There were no statistically significant differences between CER values for crossectomy and phlebectomy.  Conclusion. It was established that if there are no medical contraindications, it is economically feasible to carry out pharmacotherapy for SVT of lower extremities, which requires the lowest costs to achieve full recovery. The pharmacoeconomic efficiency of crossectomy and phlebectomy are comparable. Актуальность. Для лечения тромбофлебита поверхностных вен (ТФПВ) нижних конечностей могут быть использованы консервативная терапия (фармакотерапия), кроссэктомия и флебэктомия или комбинация этих методов.Цель: фармакоэкономическая оценка эффективности различных вариантов терапии у пациентов с ТФПВ нижних конечностей – фармакотерапии, кроссэктомии (в сочетании с фармакотерапией) и флебэктомии (в сочетании с фармакотерапией).Материал и методы. Фармакоэкономическую оценку проводили при помощи анализа «затраты–эффективность» (англ. сosteffectiveness analysis, CEA), рассчитывая коэффициент «затраты–эффективность» (англ. cost-effectiveness ratio, CER). В качестве параметров клинической эффективности использовали наличие рецидива/прогрессирования заболевания на протяжении 3 мес после окончания лечения, динамику нормализации болевого, психологического, физического и социального факторов, а также показатели визуально-аналоговой шкалы (ВАШ). Для оценки достоверности полученных результатов проведен детерминированный многофакторный анализ чувствительности.Результаты. При использовании в качестве показателя клинической эффективности процентной доли пациентов без прогрессирования и рецидива на протяжении 3 мес после окончания терапии установлено, что медианное значение коэффициента CER для фармакотерапии (22069,01) статистически значимо ниже, чем для кроссэктомии (83353,91) и флебэктомии (95702,96) (p=0,000). При этом медиана CER для тактики кроссэктомии была статистически значимо ниже, чем для флебэктомии (p=0,003). При использовании в качестве показателя клинической эффективности динамики нормализации болевого, психологического, физического, социального факторов и показателей ВАШ значение CER для тактики фармакотерапии было статистически значимо ниже, чем для кроссэктомии и флебэктомии. Между коэффициентами CER для кроссэктомии и флебэктомии не выявлено статистически значимых отличий.Заключение. Установлено, что если отсутствуют медицинские противопоказания, то экономически целесообразно проводить фармакотерапию ТФПВ нижних конечностей, при которой требуются наименьшие затраты для достижения единицы эффективности. Фармакоэкономическая эффективность кроссэктомии и флебэктомии сопоставимы

High-temperature studies of the magnetic susceptibility of samarium and the Al2Sm compound

This study was supported financially by the Russian Foundation for Basic Research (project no. 11-03-00469-a).The magnetic susceptibility of metallic samarium and the Al2Sm intermetallic compound has been experimentally studied by the Faraday method in the temperature range of 300-1800 K. It has been shown that the temperature dependences of the magnetic susceptibility of Sm and Al2Sm in a crystalline state can be described in the framework of Van Vleck paramagnetism theory taking into account variable valence and the contribution from the conduction electrons. Using this theoretical interpretation of the data, the effective valence of samarium in the metallic state and in the Al2Sm intermetallic compound has been estimated as a function of the temperature

Magnetic susceptibility and parameters of electronic structure of al2rem (gd, dy, and ho) intermetallic compounds at high temperatures

This work was supported in part by the Special Federal Program NK-255-P/1 and Russian Foundation for Basic Research (grant No. 09-03-90450-Ukr).The magnetic susceptibility of Al2REM (REM = Gd, Dy, and Ho) intermetallic compounds is experimentally investigated by the Faraday method in a wide temperature interval (290-2000 K) in different magnetic fields (0.3-1.3 T). In the crystalline state, the temperature dependences of the susceptibility follow the generalized Curie-Weiss law. In the liquid phase, the magnetic susceptibility of these intermetallic compounds above the melting point increases for all examined samples. The parameters of the electronic structure of the compounds are calculated based on the experimental data. It is established that the effective magnetic moment per rare-earth metal atom is smaller than that characteristic of the free REM+ ion

Magnetic susceptibility of Al2RE compounds in crystal and liquid states

Project supported by RFBR (Grant N N 09-03-90450-Ukr) and FTP (NK-255P/1, NK-16P/1)Magnetic susceptibility of Al2RE (RE=Y, Ce, Sm, Gd, Dy, Ho, Yb) compounds was studied experimentally in wide temperature (T=290-2000 K) and field (B=0.3-1.3 T) intervals. The abnormal increase in susceptibility beginning above the melting point was fixed for all the compositions. The values for the effective magnetic moments per RE atoms in these compounds were found to be smaller than the values typical for free ions RE3+. The results were discussed in supposition of the directed bonds between aluminum and rare-earth atoms