Synthesis of new organoelement copolymers based on polydimethylsiloxanes and aminophosphonates

© 2018 Based on commercially available 3-Aminopropyl (diethoxy)methylsilane new alkoxysilane with functional aminophosphonate group - diethyl (2-((3-(diethoxy (methyl)silyl)propyl)amino)propan-2-yl)phosphonate were synthesized and characterized. Obtained functional alkoxysilane were transformed to tetrasiloxane in active medium in the presence of acetic acid and then copolymerized with octamethylcyclotetrasiloxane (D4). The chemical structure of the resulting polymer was studied and confirmed by a combination of physical methods, namely,1H,13C,31P and29Si NMR, GPC, and IR spectroscopy. The thermophysical and rheological properties of the polymer were also studied

High magnetic field transport measurement of charge-ordered Pr0.5_{0.5}Ca0.5_{0.5}MnO3_3 strained thin films

We have investigated the magnetic-field-induced phase transition of charge-ordered (CO) Pr$_{0.5}$Ca$_{0.5}$MnO$_3$ thin films, deposited onto (100)-oriented LaAlO$_3$ and (100)-oriented SrTiO$_3$ substrates using the pulsed laser deposition technique, by measuring the transport properties with magnetic fields up to 22T. The transition to a metallic state is observed on both substrates by application of a critical magnetic field ($H_C>10T$ at 60K). The value of the field required to destroy the charge-ordered insulating state, lower than the bulk compound, depends on both the substrate and the thickness of the film. The difference of the critical magnetic field between the films and the bulk material is explained by the difference of in-plane parameters at low temperature (below the CO transition). Finally, these results confirm that the robustness of the CO state, depends mainly on the stress induced by the difference in the thermal dilatations between the film and the substrate.Comment: 10 pages, 6 figures. To be published in Phys. Rev.

МАГНИТНЫЕ И ТЕРМИЧЕСКИЕ СВОЙСТВА НАНОМАТЕРИАЛОВ НА ОСНОВЕ ВЫСОКОРАЗВЕТВЛЕННЫХ ФЕРРОЦЕНСОДЕРЖАЩИХ ПОЛИМЕРОВ

New magnetic nanomaterials with magnetization up to 32 Gs·cm3/g were synthesized from highly branched ferrocene-containing polymers by thermal structural transformations in a field of 2.5 kOe. The structure and properties of the prepared polymers were studied by IR spectroscopy, transmission electron microscopy (TEM) and thermogravimetric analyses. According to IR spectroscopy the content of 1,3,5-substituted benzene rings in the ferrocene-containing polymer increases at 500°C. X-ray diffraction study showed that iron in such a sample is present exclusively in the form of Fe3O4 magnetite. As the heating temperature increased to 600°C, the composition of the samples became more complex: along with magnetite they contain cementite Fe3C and wustite FeO.97O. The magnetization of the ferrocene-containing polymer depends on the synthesis and heat treatment temperature. For a sample synthesized at 140°C the formation of a magnetically ordered phase begins at 500°C, and at 800°C the magnetization reaches a maximum value of 32 Gs·cm3/g. The average size of magnetic particles according to TEM analysis was 8-26 nm. The principal possibility of controlling the size and composition of the nanoparticles, as well as their magnetization depending on the conditions of production and the temperature of polymer structuring is shown. The obtained results provide a good basis for the directed synthesis of magnetic ferrocene-containing polymers with preset characteristics.Термоструктурированием высокоразветвленных ферроценсодержащих полимеров синтезированы новые магнитные наноматериалы с намагниченностью насыщения до 32 Гс·см3/г в магнитном поле 2.5 килоэрстед. Исследованы структура и свойства полученных соединений методами ИК-спектроскопии, просвечивающей электронной микроскопии (ПЭМ) и термогравиметрического анализа. По данным ИК-спектроскопии в ферроценсодержащем полимере, прогретом при 500 °С, содержание 1,3,5-замещенных бензольных колец возрастает. Рентгенодифракционное исследование показало, что железо в таком образце присутствует исключительно в форме магнетита Fe3O4. С повышением температуры прогрева до 600 °С состав образцов становился более сложным, наряду с магнетитом в них содержался цементит Fe3C и вюстит Fe0.97O. Намагниченность ферроценсодержащего полимера зависит от температуры синтеза и термообработки. Для образца, синтезированного при температуре 140 ºС, образование магнитоупорядоченной фазы начинается при прогреве от 500 ºС, и при 800 ºС намагниченность достигает максимального значения 32 Гс·см3/г. Среднестатистические размеры магнитных наночастиц по данным ПЭМ составляют 8-26 нм. Показана принципиальная возможность контроля размера и состава наночастиц, а также их намагниченности, в зависимости от условий получения и температуры структурирования полимеров. Полученные результаты создают хорошую основу направленного синтеза магнитных ферроценсодержащих полимеров с заданными характеристиками

Ледотехнические аспекты создания объектов транспортной инфраструктуры и разведочного бурения в Арктике

Starting from the mid 2000-s the increase of sustained development of the Russian Arctic is observed, in many cases the technologies using the ice cover as an infrastructure element and the ice as the construction materials are used. In the present time the different approaches of use of natural and artificial ice for applied tasks on the Arctic offshore exist. For example, the clearance of the upper surface of ice from snow and ridges is used for the purposes of the vessel unloading on the fast ice or constructing the airstrips on the drifting ice cover. In case of insufficient thickness of the level ice the latter is increased by the means of preliminary freezing (natural on the bottom side of ice and artificial by pouring the fresh or saline water on the upper surface). By constructing the artificial ice islands the ice body is made by spraying the sea water with the partial freezing of the water drops in the air and further freezing of the 2-phase elements (i.e. ice crystals in the liquid film) on the surface of the ice cover. The problem of cracks in the ice cover is solved by different means according to the proper task. When it is possible, the cracks are “healed”— i.e. are filled with the snow and ice gravel and then freezed. In case of impossibility of use of such method (for example — presence of tidal cracks or relatively high air temperature) the cracks are overlapped with the help of different covers made of different materials and of different sizes. The promising trend of ice technology is involving the reinforced or composite ice, having the increased strength, into the ice engineering practice. By unloading the cargo ships on the fast ice the ice strength is decreased locally for the purpose of easy berthing of the vessel with safekeeping the original strength of the surrounding ice for the aims of the vessel unloading. This problem is solved by creating the system of notches in the ice cover according to the vessel dimensions. The specialized hydrometeorological support on every stage of the ice engineering operation is an essential element of the ice engineering activities on the ice cover of lakes, rivers and seas.Рассматриваются направления ледотехники, связанные с использованием ледяного покрова природных водоемов как несущей площадки для создания транспортной инфраструктуры (ледовые причалы, аэродромы, искусственные ледяные острова и т.п.). Обсуждаются общие вопросы организации и проведения инженерно-технических работ на льду и некоторые частные проблемы, связанные с решением отдельных конкретных задач. Особое внимание уделено специальному гидрометеорологическому обеспечению операций как неотъемлемой части ледотехнических работ

Three Ways of Combining Genotyping and Resequencing in Case-Control Association Studies

We describe three statistical results that we have found to be useful in case-control genetic association testing. All three involve combining the discovery of novel genetic variants, usually by sequencing, with genotyping methods that recognize previously discovered variants. We first consider expanding the list of known variants by concentrating variant-discovery in cases. Although the naive inclusion of cases-only sequencing data would create a bias, we show that some sequencing data may be retained, even if controls are not sequenced. Furthermore, for alleles of intermediate frequency, cases-only sequencing with bias-correction entails little if any loss of power, compared to dividing the same sequencing effort among cases and controls. Secondly, we investigate more strongly focused variant discovery to obtain a greater enrichment for disease-related variants. We show how case status, family history, and marker sharing enrich the discovery set by increments that are multiplicative with penetrance, enabling the preferential discovery of high-penetrance variants. A third result applies when sequencing is the primary means of counting alleles in both cases and controls, but a supplementary pooled genotyping sample is used to identify the variants that are very rare. We show that this raises no validity issues, and we evaluate a less expensive and more adaptive approach to judging rarity, based on group-specific variants. We demonstrate the important and unusual caveat that this method requires equal sample sizes for validity. These three results can be used to more efficiently detect the association of rare genetic variants with disease

Production of {\pi}+ and K+ mesons in argon-nucleus interactions at 3.2 AGeV

First physics results of the BM@N experiment at the Nuclotron/NICA complex are presented on {\pi}+ and K+ meson production in interactions of an argon beam with fixed targets of C, Al, Cu, Sn and Pb at 3.2 AGeV. Transverse momentum distributions, rapidity spectra and multiplicities of {\pi}+ and K+ mesons are measured. The results are compared with predictions of theoretical models and with other measurements at lower energies.Comment: 29 pages, 20 figure

The effectiveness of the russian healthcare system during the covid-19 epidemic: Public opinion

The article is devoted to the availability and quality of medical care of the population during the COVID-19 epidemic in the Russian Federation. The authors, based on the analysis of the opinion of the population participated in the study conducted in 2020, came to the conclusion that the Russian health care system work in the situation of the COVID-19 epidemic, as a whole, can be con-sidered as satisfactory: the major part of population assessed an access to and quality of medical care at quite high level in all types of medical organizations. Thus, the Russian health care system has shown its ability to respond effectively and promptly to the emer-gency situation, to mobilize personnel, medical and technical resources for it in the shortest possible time, and to provide the population with timely and high-quality medical care

Typology of regional media space

Статья посвящена актуальным проблемам типологизации регионального медиапространства страны для стандартизации управленческой среды. Анализируется одна из возможных кластерных структур, построенная на основе социально-экономических, демографических и медийных переменных.The article is devoted to topical problems of typology of regional media space of the country for the standardization of the management of the environment. The author analyses one of the possible cluster structures, built on the basis of socioeconomic, demographic and media variables