Anomalous optical phonons in FeTe pnictides: spin state, magnetic order, and lattice anharmonicity

Polarized Raman-scattering spectra of non-superconducting, single-crystalline FeTe are investigated as function of temperature. We have found a relation between the magnitude of ordered magnetic moments and the linewidth of A1g phonons at low temperatures. This relation is attributed to the intermediate spin state (S=1) and the orbital degeneracy of the Fe ions. Spin-phonon coupling constants have been estimated based on microscopic modeling using density-functional theory and analysis of the local spin density. Our observations show the importance of orbital degrees of freedom for the Fe-based superconductors with large ordered magnetic moments, while small magnetic moment of Fe ions in some iron pnictides reflects the low spin state of Fe ions in those systems.Comment: 17 pages, 3 figure

Белково-липидный состав пыльцы березы бородавчатой (Betula verrucosa) и ее антиоксидантная активность в зависимости от места произрастания

Pollen has various effects on the human body. In order to study and compare the biological activity of the mature pollen grains of Betula verrucosa Ehrh. we investigated the protein-lipid composition and total antioxidant activity (TAA) of 10 samples from different habitats in the territory of Ukraine and the Slovak Republic. The collection sites are near highways and apartment blocks, as well as a nature reserve, forest and botanical garden. The protein content was determined by the Kjeldahl method. A chromatographic analysis of fatty acids from lipids was performed using a “Cvet 500” gas chromatograph, equipped with a flame-ionization detector in the isothermal mode. The bioactivity of aqueous, ethanol and methanol extracts of pollen grains was evaluated by the DPPH free radical scavenging method (2,2-diphenyl-1-picrylhydrazyl) by means spectrophotometry in vitro. The protein content of the pollen of B. verrucosa ranged from 17.9% to 25.6%, depending on the habitat. Unsaturated fatty acids were found in higher amounts than saturated fatty acids. The profile of fatty acids indicates a higher content of palmitic (33.9%), oleic (29.5%) and linoleic (27.8%) acids and a low content of arachidonic (0.4%) and pentadecanoic (0.8%) acids. We also established that silver birch pollen is characterized by high antioxidant activity. The measured value of TAA for aqueous pollen extracts was within 74.8–85.5%. For the ethanol extracts it was quantified within 60.3–95.0% and for the methanol extracts – 46.1–92.6%. The Tukey test was used to determine the differences between the means at a level of P < 0.05. A strong correlation coefficient (0.70) was defined between the protein content and the TAA of aqueous extracts. In general, the Ukrainian and Slovak samples of pollen differ in the fatty acid composition of lipids and aqueous and ethanol TAA extracts. Pollen of B. verrucosa should be used for diagnostic, therapeutic and prophylactic purposes as close as possible to the place of origin. Исследованы белковый и липидный состав и биологическая активность 10 образцов пыльцы Betula verrucosa Ehrh. из разных мест произрастания на территории Украины и Словакии. Определено содержание белков (17,9–25,6%) и 8 жирных кислот (с числом углеродных атомов от 14 до 20) в составе липидов. Выявлено преобладание ненасыщенных жирных кислот (58,6%) с доминированием пальмитиновой (33,9%), олеиновой (29,5%) и линолевой (27,8%). Оценена общая антиоксидантная активность водных, этаноловых и метаноловых экстрактов пыльцы березы бородавчатой с использованием свободного стабильного радикала дифенил­пикрилгидразила колориметрически в реакции in vitro. Установлены статистически достоверные различия между образцами как внутри украинских и словацких генотипов, так и между ними. Рассматриваются факторы влияния на вариации белково-липидного состава пыльцы и ее биологической активности.Исследованы белковый и липидный состав и биологическая активность 10 образцов пыльцы Betula verrucosa Ehrh. из разных мест произрастания на территории Украины и Словакии. Определено содержание белков (17,9–25,6%) и 8 жирных кислот (с числом углеродных атомов от 14 до 20) в составе липидов. Выявлено преобладание ненасыщенных жирных кислот (58,6%) с доминированием пальмитиновой (33,9%), олеиновой (29,5%) и линолевой (27,8%). Оценена общая антиоксидантная активность водных, этаноловых и метаноловых экстрактов пыльцы березы бородавчатой с использованием свободного стабильного радикала дифенил­пикрилгидразила колориметрически в реакции in vitro. Установлены статистически достоверные различия между образцами как внутри украинских и словацких генотипов, так и между ними. Рассматриваются факторы влияния на вариации белково-липидного состава пыльцы и ее биологической активности

ANALYTIC FUNCTIONS OF INFINITE ORDER IN HALF-PLANE

J. B. Meles (1979) considered entire functions with zeros restricted to a finite number of rays. In particular, it was proved that if is an entire function of infinite order with zeros restricted to a finite number of rays, then its lower order equals infinity. In this paper, we prove a similar result for a class of functions analytic in the upper half-plane. The analytic function in C+ = { : Im > 0} is called proper analytic if lim sup(z→t)⁡( ln⁡|f(z)|)≤0 for all real numbers ∈ R. The class of the proper analytic functions is denoted by . The full measure of a function ∈ is a positive measure, which justifies the term "proper analytic function". In this paper, we prove that if a function is the proper analytic function in the half-plane C+ of infinite order with zeros restricted to a finite number of rays L through the origin, then its lower order equals infinity

Phase separation in iron chalcogenide superconductor Rb0.8+xFe1.6+ySe2 as seen by Raman light scattering and band structure calculations

We report Raman light scattering in the phase separated superconducting single crystal Rb0.77Fe1.61Se2 with Tc = 32 K. The spectra have been measured in a wide temperature range 3K -500K. The observed phonon lines from the majority vacancy ordered Rb2Fe4Se5 (245) antiferromagnetic phase with TN= 525 K demonstrate modest anomalies in frequency, intensity and halfwidth at the superconductive phase transition. We identify phonon lines from the minority compressed Rb{\delta}Fe2Se2 (122) conductive phase. The superconducting gap with dx2-y2 symmetry is also detected in our spectra. In the range 0-600 cm-1 we observed the low intensive but highly polarized B1g-type background which becomes well structured under cooling. The possible magnetic or multiorbital origin of this background has been discussed. We argue that phase separation in M0.8+xFe1.6+ySe2 has pure magnetic origin. It occurs below Neel temperature when iron magnetic moment achieves some critical magnitude. We state that there is a spacer between the majority 245 and minority 122 phases. Using ab-initio spin polarized band structure calculations we demonstrate that compressed vacancy ordered Rb2Fe4Se5 phase can be conductive and therefore may serve as a protective interface spacer between the pure metallic Rb{\delta}Fe2Se2 phase and the insulating Rb2Fe4Se5 phase providing the percolative Josephson-junction like superconductivity in the whole sample of Rb0.8+xFe1.6+ySe2 Our lattice dynamics calculations show significant difference in the phonon spectra of the conductive and insulating Rb2Fe4.Se5 phases.Comment: This paper is devoted to the memory of academician Kirill Borisovich Tolpygo, prominent Physicist, Teacher and Citizen, who made a great contribution to the lattice dynamics theory and many other branches of solid state physic

Contamination of Betula verrucosa Ehrh. pollen by microorganisms, mycotoxins and heavy metals

Pollen samples of silver birch from Ukraine and Slovakia were investigated in order to estimate their contamination with heavy metals (Cd, Pb, Hg, Cr, As, Ni, Se, Co), representatives of the Enterobacteriaceae family, mesophilic aerobic bacteria, fungi and mycotoxins. The study is focused on the comparative analysis among pollen samples when complex of biotic, abiotic and anthropogenic factors in different places of growth affect. The obtained results are compared to the existing requirements. It is established excess of limits on the content of cadmium, lead, chromium, the concentrations of enterobacteria and mesophilic aerobic bacteria in some samples of birch pollen. The Tukey test was used to determine the differences between the means at a level of P < 0.05. Also in this work, the steps from collection to storage of wind-pollinated pollen were analyzed

ACILE SOL-GEL SYNTHESIS OF METAL OXIDE NANOPARTICLES IN A CELLULOSE PAPER TEMPLATE

Ensembles of free standing particles of titanium, zinc, copper and iron oxides of 6-109 nm in size were sol-gel synthesized with a use of a cellulose paper as a template. The calcination time as short as 60 min at 550 °C in air was found to be sufficient for the formation of crystalline single phase TiO2 or ZnO nanoparticles, Cu2O+CuO or Fe2O3+Fe3O4 nanocomposites and to burn out the organic components. The impurities initially present in the cellulose (Сa, Na, Cl) were detected in the synthesized compounds. The original version of the paper was stolen by James Franklin and on-line published with the cut list of the authors in Journal of Nanomedicine and Nanotechnology 2017 without author permission

The Sand Cement Composites Using Municipal Solid Waste

Секция III : Ресурсо- и энергосберегающие строительные материалы и технологииИсследования материаловедов, в последнее время, направлены на создание новых и совершенствование свойств уже зарекомендовавших себя материалов, с использованием вторичного сырья. В данной работе приведены результаты исследований по утилизации полимерных коммунальных отходов в качестве фибры в цементно-песчаных композитах на базе местного минерального сырья. Дан анализ ситуации по накоплению твердых коммунальных отходов, рассмотрены тенденции утилизации их в мировой и российской практике. Подтверждены реальные возможности использования полимерных отходов как вторичного сырья для производства строительных материалов.=Recently, research of materials scientists has been aimed at creating new and improving the properties of already proven materials using secondary raw materials. Article analysis findings on the utilization of polymer municipal waste as fibra in sand cement composites, which based on local mineral raw materi-als. Analysis of the existing state on concentration of municipal solid waste is given, tendencies of their utilization in world and Russian practice are considered. The real opportunities of using polymer wastes as secondary raw materials for the production of building materials have been confirmed

Phase separation in iron chalcogenide superconductor Rb₀.₈₊xFe₁.₆₊ySe₂ as seen by Raman light scattering and band structure calculations

We report Raman light scattering in the phase separated superconducting single crystal Rb₀.₇₇Fe₁.₆₁Se₂ with Tc = 32 K over a wide temperature region 3–500 K. The observed phonon lines from the majority vacancy ordered Rb₂Fe₄Se₅ (245) antiferromagnetic phase with TN = 525 K demonstrate modest anomalies in the frequency, intensity and halfwidth at the superconductive phase transition. We identify phonon lines from the minority compressed RbδFe₂Se₂ (122) conductive phase. The superconducting gap with dx₂₋y₂ symmetry has been detected in our spectra. In the range 0–600 cm–¹ we observe a weak but highly polarized B₁g-type backgroundwhich becomes well-structured upon cooling. A possible magnetic or multiorbital origin of this background is discussed. We argue that the phase separation in M₀.₈₊xFe₁.₆₊ySe₂ is of pure magnetic origin. It occurs below the Néel temperature when the magnetic moment of iron reaches a critical value. We state that there is a spacer between the majority 245 and minority 122 phases. Using ab initio spin-polarized band structure calculations we demonstrate that the compressed vacancy ordered Rb₂Fe₄Se₅ phase can be conductive and therefore may serve as a protective interface spacer between the purely metallic RbδFe₂Se₂ phase and the insulating Rb₂Fe₄Se₅ phase providing percolative Josephson-junction like superconductivity all throughout of Rb₀.₈₊xFe₁.₆₊ySe₂. Our lattice dynamics calculations show significant differences in the phonon spectra of the conductive and insulating Rb₂Fe₄Se₅ phases