207Pb and 17O NMR Study of the Electron Density Distribution in Metal Phase of BaPb_{1-x}Bi_xO_3

The 17O and 207Pb NMR spectra were measured in ceramic samples in the metallic phase of BaPb_{1-x}Bi_{x}O_3 oxides (0<x< 0.33). The inhomogeneous magnetic broadening which appears due to a distribution of the Knight shifts was analyzed in detail. It is shown that Bi atoms, which are randomly incorporated in BaPbO_3 parent compound give rise to an increased conduction electron spin density within an area which is delimited by its two first cation shells. According to NMR data the percolative overlap of these areas occurs in superconducting compositions and it is accompanied by a sharp growth of the average Knight shift . The decrease of with temperature revealed for x=0.33 evidences for an opening of the energy gap near E_F near the metal-semiconductor transition (x=0.35).Comment: submitted to Phys. Rev.

The charge ordered state in half-doped Bi-based manganites studied by 17^{17}O and 209^{209}Bi NMR

We present a $^{209}$Bi and $^{17}$O NMR study of the Mn electron spin correlations developed in the charge ordered state of Bi$_{0.5}$Sr$_{0.5}$MnO$_{3}$ and Bi$_{0.5}$Ca$_{0.5}$MnO$_{3}$. The unusually large local magnetic field $^{209}H_{loc}$ indicates the dominant $6s^{2}$ character of the lone electron pair of Bi$^{3+}$-ions in both compounds. The mechanism connecting the $s$ character of the lone pairs to the high temperature of charge ordering $T_{CO}$ is still not clarified. The observed difference in $^{209}H_{loc}$ for Bi$_{0.5}$Sr$_{0.5}$MnO$_{3}$ to Bi$_{0.5}$Ca$_{0.5}$MnO$_{3}$ is probably due to a decrease in the canting of the staggered magnetic moments of Mn$^{3+}$-ions from. The modification of the $^{17}$O spectra below $T_{CO}$ demonstrates that the line due to the apical oxygens is a unique local tool to study the development of the Mn spin correlations. In the AF state the analysis of the $^{17}$O spectrum of Pr$_{0.5}$Ca$_{0.5}$MnO$_{3}$ and Bi$_{0.5}$Sr$_{0.5}$MnO$_{3}$ prompts us to try two different theoretical descriptions of the charge-ordered state, a site-centered model for the first manganite and a bond-centered model for the second one.Comment: 10 pages, 7 figure

Динамика геомагнитных пульсаций, продольных токов и свечения ночной атмосферы на средних широтах во время суббуревых активизаций в ходе супербурь

Within substorm activations during two superstorms (2000 and 2003) from the observations at mid-latitude geomagnetic observatories, we study short-period irregular geomagnetic pulsations and airglow in the 557.7 nm and 630.0 nm atomic oxygen emission lines, and in the 391.4 nm ionized nitrogen molecular band. Through the genuine magnetogram inversion technique, from the 1-minute data of the ground-based magnetometer global network, we investigate the distribution dynamics for field-aligned currents (FACs) in the ionosphere. The relation is shown between pulsation bursts and airglow disturbances in the post-midnight sector to precipitations of energetic electrons (~keV) and increase in the R2 upward FACs.Во время суббуревых активизаций в ходе двух супербурь 2000 и 2003 гг. по данным наблюдений среднеширотных геомагнитных обсерваторий ИСЗФ СО РАН (Монды, Узур) и обсерватории Борок ИФЗ РАН исследуются короткопериодные иррегулярные геомагнитные пульсации, а также свечение ночной атмосферы в эмиссионных линиях кислорода 557.7, 630.0 нм и молекулярной полосе ионизованного азота 391.4 нм (по оптическим данным геофизической обсерватории ИСЗФ СО РАН Торы). С помощью оригинальной техники инверсии магнитограмм ИСЗФ по одноминутным данным мировой сети наземных магнитометров исследуется динамика распределения плотности продольных токов в ионосфере. Показана связь всплесков пульсаций и возмущений в свечении атмосферы в послеполуночном секторе с высыпанием энергичных электронов (~кэВ) и усилением вытекающих продольных токов зоны R2

Spin Susceptibility of Ga-Stabilized delta-Pu Probed by {69}^Ga NMR

Spin susceptibility of stabilized \delta phase in the Pu-Ga alloy is studied by measuring {69,71}^Ga NMR spectra and nuclear spin-lattice relaxation rate {69}T_{1}^{-1} in the temperature range 5 - 350 K. The shift ({69}^K) of the {69,71}^Ga NMR line and {69}^T_{1}^{-1} are controlled correspondingly by the static and the fluctuating in time parts of local magnetic field arisen at nonmagnetic gallium due to transferred hyperfine coupling with the nearest f electron environment of the more magnetic Pu. The nonmonotonic with a maximum around 150 K behavior of {69}^K(T) \chi_{s,5f}(T) is attributed to the peculiarities in temperature dependence of the f electron spin susceptibility \chi_{s,5f}(T) in \delta phase of plutonium. The temperature reversibility being observed in {69}^K(T) data provides strong evidence for an electronic instability developed with T in f electron bands near the Fermi energy and accompanied with a pseudogap-like decrease of \chi_{s,5f}(T) at T<150 K. The NMR data at high temperature are in favor of the mainly localized character of 5f electrons in \delta phase of the alloy with characteristic spin-fluctuation energy \Gamma(T) T^{0.35(5)}, which is close to $\Gamma(T) T^{0.5} predicted by Cox et al. [J. Appl. Phys. 57, 3166 (1985)] for 3D Kondo-system above T_Kondo}. The dynamic spin correlations of 5f electrons become essential to consider for {69}^T_{1}^{-1}(T) only at T<100 K. However, no NMR evidences favoring formation of the static magnetic order in \delta-Pu were revealed down to 5K .Comment: 6 pages, 4 figure

Composition-, temperature- and pressure-induced transitions between high-pressure stabilized perovskite phases of the (1-x)BiFe0.5Sc0.5O3 - xLaFe0.5Sc0.5O3 series

Crystal structures of the high-pressure synthesized perovskite phases of the (1-x)BiFe0.5Sc0.5O3-xLaFe0.5Sc0.5O3 (0 ​= ​x ​≤ ​1) system and their temperature and pressure behaviours were studied using laboratory and synchrotron X-ray diffractions as well as neutron diffraction. At room temperature, the as-prepared phases with x ​≤ ​0.05 have an antipolar structure with the Pnma symmetry and with the √2ap ​× ​4ap ​× ​2√2ap superstructure (where ap is the pseudocubic perovskite unit-cell parameter). An incommensurately modulated phase with the Imma(00γ)s00 superspace group is observed for 0.10 ​= ​x ​≤ ​0.33, while a non-polar Pnma phase (√2ap ​× ​2ap ​× ​√2ap) is stable when x ​≥ ​0.34. The antipolar Pnma phase in the as-prepared samples with composition corresponding to x ​= ​0 transforms into the polar Ima2 one via irreversible annealing-caused transformation accompanied by a formation of a high-temperature intermediate polar R3c polymorph, while the antipolar Pnma phase in samples with x ​= ​0.05 is stable until the decomposition temperature. In the solid solutions with 0.10 ​= ​x ​≤ ​0.33, increasing temperature was found to result in a reversible transformation of the Imma(00γ)s00 phase into a non-polar Pnma one. The transition temperature decreases with increasing x. A hydrostatic pressure of few GPa was also shown to induce a reversible Imma(00γ)s00 → Pnma transformation.publishe

ОСОБЕННОСТИ ПАМЯТИ У ДЕТЕЙ ДОШКОЛЬНОГО ВОЗРАСТА С ПОСЛЕДСТВИЯМИ ПЕРИНАТАЛЬНЫХ ПОРАЖЕНИЙ ЦЕНТРАЛЬНОЙ НЕРВНОЙ СИСТЕМЫ

The ability of memory was investigated in 524 children, aged 4 to 7; with remote consequences of perinatal damage of the central nervous system (CNS). A weak memory ability was detected in 42% of children with dysfunctions of the general and fine motility and in 59% of children with impaired speech. Severe gestosis, anemia in pregnancy (stage II) and a delayed intrauterine fetal development were found to have a negative influence on memory shaping process.Изучены особенности памяти у 524 детей в возрасте от 4 до 7 лет, имеющих отдаленные последствия перинатального поражения центральной нервной системы. Слабый уровень памяти выявлен у 42% детей с нарушением общей и тонкой моторики и у 59% детей с нарушением речи. Установлено негативное влияние на процесс формирования памяти угрозы прерывания беременности, выраженной анемии беременных (II степень), гестоза и задержки внутриутробного развития плода

INVESTIGATION OF MAGNETIC NANOPARTICLES Fe0.5Co0.5 BY RESONANCE SPECTROSCOPY

Nanoparticles Fe0.5Co0.5 were synthesized by the gas-phase method, part of the sample was annealed. The NMR spectra of 59Co and NGR 57Fe have been obtained, and the magnet-ization and effective surface of the nanoparticles have been measured. The 59Co NMR spectra are inhomogeneously broadened lines.Работа выполнена в рамках государственных тем «Функция» № АААА-А19-119012990095-0, «Магнит» No АААА-А18-118020290129-5 и «Сплавы» № АААА-А19-119070890020-3)

Влияние гуминовых веществ угля и биокомпозиций с наночастицами серебра на их основе на баланс аргинина в перитонеальных макрофагах интактных мышей

Background. Antigen-presenting cells (APCs), especially macrophages, play an important role in the body defense against various pathogens. Their dysfunction and polarization are associated with most inflammatory and autoimmune diseases. The inflammatory process is regulated by activation and / or inhibition of genes differentially expressed by macrophages. Successful correction of inflammation leads firstly to elimination of inflammatory stimuli and then to remodeling and restoration of tissues and organs. It was experimentally confirmed that silvercontaining bionanocomposites based on natural humic substances (HS) obtained from coal of different origin, as well as initial matrices of these HS, are capable of activating pro- and anti-inflammatory properties of macrophages.Aim. To study cytotoxic, pyrogenic, and immunomodulatory properties (arginine balance) of initial HS samples and samples of silver nanoparticles ultradispersed in these HS matrices (HS-AgNPs) in the cell culture of peritoneal macrophages, as well as their effect on pro- and anti-inflammatory properties of APCs.Materials and methods. Cultural and biochemical methods were used in the study.Results. The study showed that the samples CHE-K, CHE-AgNPs, CHS-K, and CHP-K increased M1 macrophage polarization due to stimulation of the NO-synthase activity and inhibition of arginase. The samples CHI-K, CHIAgNPs, CHP-AgNPs, and CHS-AgNPs modulated an alternative M2 or M2-like state of macrophage activation. At the same time, HS are not cytotoxic at effective concentrations, and three out of four studied samples did not contain pyrogenic impurities.Conclusion. The use of HS and their silver-containing bionanocomposites, which have the ability to greatly affect the polarization of antigen-presenting cells, is a promising research area in correction of the inflammatory response for solving an important social and medical problem of treating chronic wounds. Введение. Антигенпрезентирующие клетки, особенно макрофаги, играют важную роль в защите организма от различных патогенов, их дисфункции, и поляризация связана с большинством воспалительных и аутоиммунных заболеваний. Воспалительный процесс жестко регулируется активацией и (или) ингибированием дифференциально экспрессируемых макрофагами генов. Успешная коррекция воспалительного процесса приводит к устранению воспалительных стимулов и далее ремоделированию и восстановлению тканей и органов. Экспериментально доказано, что биокомпозиции с наночастицами серебра на основе природных гуминовых веществ (ГВ) угля различного генеза, а также исходные матрицы данных ГВ способны активировать про- и противовоспалительные свойства макрофагов.Цель. Исследование в культуре клеток перитонеальных макрофагов цитотоксических, пирогенных и иммуномодулирующих свойств (баланс аргинина) исходных образцов ГВ и образцов наночастиц серебра, ультрадиспергированных в данных матрицах гуминовых веществ (ГВ-AgNPs),а также их влияния на про- и противовоспалительные свойства антигенпрезентирующих клеток. Материалы и методы. Использовались культуральные и биохимические методы.Результаты. Показано, что образцы CHE-K, CHE-AgNPs, CHS-K, CHP-K за счет усиления активности NOсинтазы и ингибиции аргиназы способствуют поляризации перитонеальных макрофагов по классическому типу (М1). Образцы CHI-K, CHI-AgNPs, CHP-AgNPs и CHS-AgNPs модулируют альтернативный М2 или M2-подобный тип (M2-like state) активации макрофагов. При этом ГВ не цитотоксичны в эффективных концентрациях, а также три из четырех исследуемых образцов не содержат пирогенных примесей.Заключение. Применение ГВ и серебросодержащих бионанокомпозиций на основе ГВ, обладающих способностью широко влиять на поляризацию антигенпрезентирующих клеток, является перспективным направлением исследований коррекции воспалительной реакции и, в частности, для решения острой социальной и медицинской проблемы – лечения хронических ран.