Dominant ferromagnetism in the spin-1/2 half-twist ladder 334 compounds, Ba3Cu3In4O12 and Ba3Cu3Sc4O12

The magnetic properties of polycrystalline samples of Ba3Cu3In4O12 (In-334) and Ba3Cu3Sc4O12 (Sc-334) are reported. Both 334 phases have a structure derived from perovskite, with CuO4 squares interconnected to form half-twist ladders along the c-axis. The Cu-O-Cu angles, ~ 90o, and the positive Weiss temperatures indicate the presence of significant ferromagnetic (FM) interactions along the Cu ladders. At low temperatures, T < 20 K, sharp transitions in the magnetic susceptibility and heat capacity measurements indicate three-dimensional (3D) antiferromagnetic (AFM) ordering at TN. TN is suppressed on application of a field and a complex magnetic phase diagram with three distinct magnetic regimes below the upper critical field can be inferred from our measurements. The magnetic interactions are discussed in relation to a modified spin-1/2 FM-AFM model and the 334 half-twist ladder is compared to other 2-rung ladder spin-1/2 systems.Comment: 20 pages, 7 figure

Crystal chemical simulation of superconductors on the basis of oxide and intermetallic layers

Simulation of 'hybrid' superconductors of 3d-, 4d- and 5d-transition elements consisting of two different superconducting fragments located between positively charged ions planes - B'O2 oxide planes and B2C2 intermetallic layers - has been performed on the basis of the structure of Sr2Mn3As2O2 (A2(B2C2)(B'O2)). The oxide planes are similar to those of CuO2 in high-temperature superconducting cuprates while the intermetallic layers - to those of Ni2B2 in low-temperature superconducting borocarbides RNi2B2C and Fe2As2 layers in high-temperature superconducting oxypnictides RFeAsO1-xFx.Comment: Title changed by the Editor of Supercond. Sci. Technol., published versio

Superconducting properties of sulfur-doped iron selenide

The recent discovery of high-temperature superconductivity in single-layer iron selenide has generated significant experimental interest for optimizing the superconducting properties of iron-based superconductors through the lattice modification. For simulating the similar effect by changing the chemical composition due to S doping, we investigate the superconducting properties of high-quality single crystals of FeSe$_{1-x}$S$_{x}$ ($x$=0, 0.04, 0.09, and 0.11) using magnetization, resistivity, the London penetration depth, and low temperature specific heat measurements. We show that the introduction of S to FeSe enhances the superconducting transition temperature $T_{c}$, anisotropy, upper critical field $H_{c2}$, and critical current density $J_{c}$. The upper critical field $H_{c2}(T)$ and its anisotropy are strongly temperature dependent, indicating a multiband superconductivity in this system. Through the measurements and analysis of the London penetration depth $\lambda _{ab}(T)$ and specific heat, we show clear evidence for strong coupling two-gap $s$-wave superconductivity. The temperature-dependence of $\lambda _{ab}(T)$ calculated from the lower critical field and electronic specific heat can be well described by using a two-band model with $s$-wave-like gaps. We find that a $d$-wave and single-gap BCS theory under the weak-coupling approach can not describe our experiments. The change of specific heat induced by the magnetic field can be understood only in terms of multiband superconductivity.Comment: 13 pages, 7 figure

Melting of the orbital order in LaMnO3 probed by NMR

The Mn spin correlations were studied near the O′-O phase transition at TJT=750 K up to 950 K with 17O and 139La NMR in a stoichiometric LaMnO3 crystalline sample. The measured local hyperfine fields originate from the electron density transferred from the eg and t2g orbitals to the 2s(O) and 6s(La) orbits, respectively. By probing the oxygen nuclei, we show that the correlations of the Mn spins are ferromagnetic in the ab plane and robust up to TJT, whereas along the c axis they are antiferromagnetic and start to melt below TJT, at about 550 K. Above TJT, the ferromagnetic Mn-Mn exchange interaction is found isotropic. The room-temperature orbital mixing angle, φNMR= 109±1.5â̂̃, of the eg ground state is close to the reported value which was deduced from structural data on Jahn-Teller distorted MnO6 octahedra. For T>TJT, LaMnO3 can be described in terms of nonpolarized eg orbitals since both eg orbitals are equally occupied. © 2013 American Physical Society

СРАВНИТЕЛЬНЫЙ АНАЛИЗ ЭФФЕКТИВНОСТИ ИСПОЛЬЗОВАНИЯ РАЗЛИЧНЫХ ВИДОВ ДРОЖЖЕЙ В СПИРТОВОМ ПРОИЗВОДСТВЕ

The paper shows the feasibility and efficiency of using new species and races of yeast in alcohol production and the yeast isolated from bioculture of rice fungus in particular. The yeast under study is characterized by favorable technological properties and high alcohol accumulation as well as low formation of ethanol extraneous admixtures responsible for its quality.В статье показана целесообразность и эффективность использования в спиртовом производстве новых видов и рас дрожжей, в частности, дрожжей, выделенных из биокультуры рисового гриба. Изучаемые дрожжи характеризуются высокими технологическими свойствами и повышенным спиртонакоплением в сочетании с низким образованием побочных примесей этанола, отвечающих за его качество

Endocrine aspect of overtraining in athletes

Striving to achieve the goals of the training process with the irrational use of physical activity can lead to a decrease in the adaptive and reserve capabilities of the athlete. The development of changes in the endocrine, cardiovascular and central nervous systems may result in the development of overtraining syndrome. There is no unified approach to the definition, diagnosis, treatment and prevention of overtraining syndrome in the literature up to the present day. The endocrine aspects of the development of the overtraining syndrome are not sufficiently studied. In particular, there is no clear understanding of the degree of involvement of various hormonal mechanisms in its pathogenesis and ideas about the possibilities of using hormone levels to diagnose this condition. The purpose of this publication is to summarize and systematize the available concepts regarding the endocrine aspects of the overtraining syndrome

Pathlength distribution of atmospheric neutrinos

We present the distribution of the production heights of atmsopheric neutrinos as a function of zenith angle and neutrino energy. The distributions can be used as the input for evaluation of neutrino propagation under various hypotheses for neutrino flavor oscillations.Comment: REVTeX file with 5 postscript figure

Внутрибрюшинное введение клеточно-инженерной конструкции поджелудочной железы крысам с экспериментальным сахарным диабетом (предварительные результаты)

Creation of a bioartificial pancreas, including a cell-engineered construct (CEC) formed from pancreatic islets (islets of Langerhans) and a biocompatible matrix mimicking the native microenvironment of pancreatic tissue, is one of the approaches to the treatment of type 1 diabetes mellitus (T1D).Objective: to conduct preliminary in vivo studies of the functional efficacy of intraperitoneal injection of a cell-engineered pancreatic endocrine construct and a suspension of rat pancreatic islets in an experimental T1D model.Materials and methods. Tissue-specific scaffold was obtained by decellularization of human pancreatic fragments. The viability and functional activity of rat islets isolated with collagenase were determined. Experimental T1D was modeled by intraperitoneal injection of low-dose streptozotocin and incomplete Freund’s adjuvant into rats. The rats were intraperitoneally injected twice with pancreatic CEC (n = 2) or islet suspension (n = 1). Glucose levels in the blood and urine of the rats were assessed. Histological examination of organs (pancreas and kidneys) of the experimental animals was carried out.Results. After the first injection, blood glucose levels gradually decreased in all animals by more than 47% of the initial values; by follow-up day 24, the glucose level rose to the initial hyperglycemic values. After repeated administration, a 63.4% decrease in glycemic level was observed in the rats with pancreatic CEC and a 47.5% decrease in the one with islet suspension. At week 5 of the experiment, blood glucose levels gradually increased in all animals. At the same time, the glycemic index of the rat with injected pancreatic CEC was 62% lower than the glycemic index of the rat with injected islets.Conclusion. Allogeneic pancreatic islets in pancreatic CEC increase the duration of stable glycemic level in T1D rats.Создание биоискусственной поджелудочной железы (ПЖ), в том числе клеточно-инженерной конструкции (КИК), сформированной на основе островков Лангерганса и биосовместимого матрикса, имитирующего нативное микроокружение панкреатической ткани, является одним из подходов к лечению сахарного диабета I типа (СД I).Целью работы было проведение предварительных исследований in vivo функциональной эффективности внутрибрюшинного введения клеточно-инженерной конструкции эндокринного отдела поджелудочной железы и суспензии панкреатических островков крысы в экспериментальной модели СД I.Материалы и методы. Тканеспецифический матрикс получали в результате децеллюляризации фрагментов ПЖ человека. Определяли жизнеспособность и функциональную активность островков крысы, выделенных с помощью коллагеназы. Экспериментальный СД I моделировали путем внутрибрюшинного введения малых доз стрептозотоцина и неполного адъюванта Фрейнда крысам. Крысам дважды вводили внутрибрюшинно КИК ПЖ (n = 2) или суспензию островков (n = 1). Оценивали уровень глюкозы в крови и моче крыс, а также проводили гистологическое исследование органов (поджелудочная железа и почки) экспериментальных животных.Результаты. После первого введения отмечали постепенное снижение уровня глюкозы в крови всех животных более чем на 47% от исходных значений, у которых к 24 суткам наблюдения происходил подъем уровня глюкозы до исходных гипергликемических показателей. После повторного введения наблюдали снижение уровня гликемии у животных с КИК ПЖ на 63,4% и на 47,5% – у крысы с суспензией островков. Через 5 недель эксперимента происходило постепенное повышение уровня глюкозы в крови у всех животных. При этом гликемический показатель крысы с введенной КИК ПЖ был на 62% ниже показателя гликемии у крысы с введенными островками.Заключение. В предварительных экспериментах показано, что аллогенные панкреатические островки в составе КИК ПЖ увеличивают длительность стабильного уровня гликемии у крыс с СД I

Electronic structure and magnetic properties of the strong-rung spin-1 ladder compound Rb3 Ni2(NO3)7

Rb3Ni2(NO3)7 was obtained by crystallization from anhydrous nitric acid solution of rubidium nitrate and nickel nitrate hexahydrate. The crystal structure determined on single crystals implies isolated spin-1 two-leg ladders of Ni2+ ions connected by (NO3)- groups as basic elements. Magnetic susceptibility, specific heat in magnetic fields up to 9 T, magnetization, and high-frequency electron spin resonance studies performed on powder samples show the absence of long-range magnetic order at T≥2 K. Electronic structure calculations and the detailed analysis of the experimental data enable quantitative estimates of the relevant parameters of the S=1 ladders in Rb3Ni2(NO3)7. The rung coupling J1=10.16 K, the leg coupling J2=1.5 K, and the Ising-type anisotropy |A|=8.6 K are obtained. The scenario of a valence-bond solidlike quantum ground state realized in the two-leg Ni2+ ladders is further corroborated by model simulations of the magnetic susceptibility. © 2018 American Physical Society