Who Killed Belikov: About the Hunting Intrigue of A. P. Chekhov's Little Trilogy

В статье рассматривается восприятие рассказа А. П. Чехова "Человек в футляре", соотнеся сюжет рассказа с близкими по смыслу чеховскими контекстами.This article aims to deautomatize the perception of A. P. Chekhov's story “The Man in a Case”, correlating the plot of the story (and the entire small trilogy) with Chekhov's contexts that are close in meaning

Фазовые превращения при кристаллизации Sr2CrMoO6–δ

The sequence of phase transformations in the process of crystallization of the Sr2CrMoO6 by the solid-phase technique from a stoichiometric mixture of simple oxides SrCO3 + 0.5Cr2O3 + MoO, has been investigated. It was determined that the synthesis of the strontium chrome-molybdate proceeds through a series of sequential-parallel stages. By means of the differential thermal analysis and thermogravimetric analysis data, it has been established that five clearly expressed endothermal effects were observed in the temperature range 300—1300 K. It was found that during the studies of the phase transformations sequence in the process of the double perovskite synthesis, SrCrO3, SrMoO4 and Sr2CrO4 are the main concomitant compounds. Herewith, it has been observed that with the annealing temperature increase from 300 to 1270 K, the complex compounds SrCrO4, SrCrO3 (350—550 K) and SrMoO4, Sr2CrO4 (600—750 K) are emerging initially and practically simultaneously. It has been revealed with a subsequent temperature increase that in the temperature range 940—1100 K, the SrMoO4, Sr2CrO4 and SrCrO3 phase concentration dramatically drops with the emerging and growth of the Sr2CrMoO6-δ double perovskite. With that in the range up to 1120—1190 K, the main XRD reflexes intensity for the SrCrO3 and SrMoO4 lowers substantially, and their content in the samples at 1170 К is no more than 7,9 %. During a consideration of the derivative of the SrCrO3, SrMoO4 and Sr2CrO4 phase transformation degree (|(dα/dt)|mах), at which their crystallization rates are maximal, it has been determined that |(dα/dt)|mах for the Sr2CrO4 corresponds to the maximal temperature 1045 K, which indicates the presence of considerable kinetic difficulties at the formation of the Sr2CrO4 phase. Thereafter this phase does not disappear and at its appearance the slowing down of the double perovskite growth takes place. On the base of investigations of the phase transformations dynamics for the obtaining of the single-phase Sr2CrMoO6-δ compound with the superstructural ordering of the Cr/Mo cations and improved magnetic characteristics, the SrCrO3 and SrMoO4 precursors were used with combined heating modes.Исследована последовательность фазовых превращений в процессе кристаллизации Sr2CrMoO6-δ из стехиометрической смеси простых оксидов SrCO3 + 0,5Cr2O3 + MoO. Установлено, что фазообразование хромомолибдата стронция протекает через ряд последовательно-параллельных стадий. Согласно данным дифференциально-термического и термогравиметрического анализов, обнаружено, что в температурном диапазоне 300—1300 К наблюдается пять ярко выраженных эндотермических эффектов. При изучении последовательности фазовых превращений в процессе синтеза двойного перовскита обнаружено, что основными сопутствующими соединениями являются SrCrO3, SrMoO4 и Sr2CrO4. При этом замечено, что с ростом температуры отжига от 300 до 1270 К в исходной смеси первоначально и практически одновременно появляются сложные соединения SrCrO4, SrCrO3 (350—550 К), а затем и SrMoO4, Sr2CrO4 (600—750 К). Показано, что с последующим увеличением температуры в интервале температур 940—1100 К концентрация фаз SrMoO4, Sr2CrO4 и SrCrO3 резко падает с появлением и ростом двойного перовскита Sr2CrMoO6-δ. При этом в интервале температур до 1120—1190 К основные рентгеновские рефлексы фазы Sr2CrO4 уменьшаются незначительно, тогда как интенсивность рентгеновских рефлексов фаз SrCrO3 и SrMoO4 снижается существенно больше и их содержание в образце при температуре 1170 К составляет не более 7,9 %. Анализ амплитудных значений производной степени превращения фаз SrCrO3, SrMoO4 и Sr2CrO4, при которых скорости их кристаллизации максимальны, показал, что для Sr2CrO4 величина |(dα/dt)|mах соответствует наибольшей температуре T = 1045 К. Это указывает на наличие кинетических трудностей при образовании фазы Sr2CrO4, которая в дальнейшем не исчезает, а при ее появлении наблюдается замедление роста двойного перовскита. На основании результатов, полученных при изучении динамики фазовых превращений для формирования однофазного Sr2CrMoO6-δ со сверхструктурным упорядочением Cr/Mo и улучшенными магнитными характеристиками, были применены прекурсоры SrCrO3 и SrMoO4 с использованием комбинированных режимов нагрева

Sequence of phase transformations at the formation of the strontium chrome-molybdate compound

The sequence of phase transformations in the process of crystallization of the Sr2CrMoO6 by the solid-phase technique from a stoichiometric mixture of simple oxides SrCO3 + 0.5Cr2O3 + MoO, has been investigated. It was determined that the synthesis of the strontium chrome-molybdate proceeds through a series of sequential-parallel stages. By means of the differential thermal analysis and thermogravimetric analysis data, it has been established that five clearly expressed endothermal effects were observed in the temperature range 300−1300 K. It was found that during the studies of the phase transformations sequence in the process of the double perovskite synthesis, SrCrO3, SrMoO4 and Sr2CrO4 are the main concomitant compounds. Herewith, it has been observed that with the annealing temperature increase from 300 to 1270 K, the complex compounds SrCrO4, SrCrO3 (350−550 К) and SrMoO4, Sr2CrO4 (600−750 К) are emerging initially and practically simultaneously. It has been revealed with a subsequent temperature increase that in the temperature range 940−1100 К, the SrMoO4, Sr2CrO4 and SrCrO3 phase concentration dramatically drops with the emerging and growth of the Sr2CrMoO6-δ double perovskite. With that in the range up to 1120–1190 К, the main XRD reflexes intensity for the SrCrO3 and SrMoO4 lowers substantially, and their content in the samples at 1170 К is no more than 7.9%. During a consideration of the derivative of the SrCrO3, SrMoO4 and Sr2CrO4 phase transformation degree (|(dα/dt)|mах), at which their crystallization rates are maximal, it has been determined that |(dα/dt)| mах for the Sr2CrO4 corresponds to the maximal temperature 1045 К, which indicates the presence of considerable kinetic difficulties at the formation of the Sr2CrO4 phase. Thereafter this phase does not disappear and at its appearance the slowing down of the double perovskite growth takes place. On the base of investigations of the phase transformations dynamics for the obtaining of the single-phase Sr2CrMoO6-δ compound with the superstructural ordering of the Cr/Mo cations and improved magnetic characteristics, the SrCrO3 and SrMoO4 precursors were used with combined heating modes

Composite Films of HDPE with SiO2 and ZrO2 Nanoparticles: The Structure and Interfacial Effects

Herein, we investigated the influence of two types of nanoparticle fillers, i.e., amorphous SiO2 and crystalline ZrO2, on the structural properties of their nanocomposites with high-density polyethylene (HDPE). The composite films were prepared by melt-blending with a filler content that varied from 1% to 20% v/v. The composites were characterized by small- and wide-angle x-ray scattering (SAXS and WAXS), small-angle neutron scattering (SANS), Raman spectroscopy, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). For both fillers, the nanoaggregates were evenly distributed in the polymer matrix and their initial state in the powders determined their surface roughness and fractal character. In the case of the nano-ZrO2 filler, the lamellar thickness and crystallinity degree remain unchanged over a broad range of filler concentrations. SANS and SEM investigation showed poor interfacial adhesion and the presence of voids in the interfacial region. Temperature-programmed SANS investigations showed that at elevated temperatures, these voids become filled due to the flipping motions of polymer chains. The effect was accompanied by a partial aggregation of the filler. For nano-SiO2 filler, the lamellar thickness and the degree of crystallinity increased with increasing the filler loading. SAXS measurements show that the ordering of the lamellae is disrupted even at a filler content of only a few percent. SEM images confirmed good interfacial adhesion and integrity of the SiO2/HDPE composite. This markedly different impact of both fillers on the composite structure is discussed in terms of nanoparticle surface properties and their affinity to the HDPE matrix