Evolution of the Crystal and Electronic Structures of the RBa 2 Cu 3 O 6 + δ Cuprates in Annealing

Abstract: The crystal structure and the magnetic properties of the HTSC cuprates YBa 2 Cu 3 O 6 + δ , Y 1 ‒   x Ca x Ba 2 Cu 3 O 6 + δ , and Nd 1 + x Ba 2 – x Cu 3 O 6 + δ (x = 0.2) with the structure of a layered perovskite are studied. The well-known aging effect detected in these HTSC materials during storage under standard conditions, namely, an increase in their critical temperature T c and a decrease in lattice parameter c in time, is investigated. Using YBa 2 Cu 3 O 6 + δ as an example, we show that the dependence of c on the oxygen content undergoes the following changes in time: (1) the negative slope of the dependence with respect to axis δ increases and (2) nonlinearity appears and grows in time according to a quadratic law. The first type of changes is explained by an increase in the valence of copper ions, which is accompanied by a decrease in their radius. The second type is explained by the electrostatic interaction of structural CuO 2 planes due to the accumulation of electron holes, which come from CuO δ planes, in them. The calculation of the second type of changes in parameter c in the YBa 2 Cu 3 O 6 + δ cuprate exhibits good quantitative agreement with the experimental data. The second-type changes in the Y 1 – x Ca x Ba 2 Cu 3 O 6 + δ compound (hole doping of CuO 2 planes) turn out to be identical to those in YBa 2 Cu 3 O 6 + δ . However, the differently directed (in time) changes in lattice parameter c in Nd 1 + x Ba 2 – x Cu 3 O 6 + δ indicate that the CuO 2 planes in the neodymium cuprate are doped by electrons at the initial stage of aging. However, when these planes are saturated with holes in time, the type of doping changes from n to p without a noticeable change in the crystal structure, which has been considered to be impossible for layered cuprates to date. © 2018, Pleiades Publishing, Inc

The Elite of Sýrnesgarðr: On the Social Stratification of the Population of the Gnyozdovo Archaeological Complex, 10th — Early 11th Centuries

Поступила в редакцию: 30.11.2022. Принята к печати: 06.04.2023.Submitted: 30.11.2022. Accepted: 06.04.2023.В статье анализируются социально-историческая топография, динамика урбанизационных трансформаций и социальная стратификация населения раннесредневекового мегаполиса в Верхнем Поднепровье X — начала XI в., носившем название *Sýrnesgarðr, ныне — Гнёздовский археологический комплекс. Это был один из крупнейших политических и торгово-ремесленных центров эпохи викингов в пределах распространения ранней древнерусской археологической культуры. Высокая степень археологической изученности этого памятника позволяет на основе введенных в научный оборот данных попытаться найти решение сложной проблемы реконструкции социальной иерархии его городского сообщества. Социум Сюрнесгарда представлял собой развитое ранговое (ранжированное) или даже раннестратифицированное общество с выраженной трехуровневой иерархией. Высшая страта использовала особые трудоемкие погребальные обряды с богатым сопровождающим инвентарем; средняя — маркировала свои погребения предметами вооружения; основная масса рядового населения практиковала различные формы «стандартных» захоронений без каких-либо эксклюзивных признаков. Анализ хронологии погребений элиты позволяет выявить два ее поколения с различными культурными установками, экономическими практиками и паттернами поведения. Первое поколение первой половины X в. проводило обряды захоронения в больших курганах и/или в лодках (ладьях), второе поколение середины — второй половины X в. — в «деревянных камерах». Смена «правящего класса» «больших курганов и ладей» на новую привилегированную группу «деревянных камер» произошла примерно в 940–960-е гг. либо после завоевания города войсками политии Рюриковичей, либо, что вероятнее, в результате внутреннего конфликта двух привилегированных групп.This paper analyses the socio-historical topography, the dynamics of urbanization transformations, and social stratification of the population of the early medieval metropolis in the Upper Dnieper area of the tenth — early eleventh centuries known as Sýrnesgarðr, nowadays the Gnyozdovo Archaeological Complex. It was one of the largest political, trade, and craft centres of the Viking Age within the spread of Old Russian archaeological culture. The high degree of archaeological knowledge of this site makes it possible to try and find a solution to the difficult problem of reconstructing the social hierarchy of its urban community referring to the data known to the scholarly community. The society of *Sýrnesgarðr was a developed ranked or even early stratified society with a pronounced three-level hierarchy. The upper stratum used special labour-intensive burial rites with rich grave goods accompanying the deceased; the middle stratum marked its burials with weapons; and the majority of the ordinary population practised various forms of “standard” burials without any exclusive features. The analysis of the chronology of the burials of the elite reveals two generations with different cultural attitudes, economic practices, and behavioural patterns. The first generation of the first half of the tenth century used burial rites in “great mounds” and/or in boats (or “rooks”). The second generation of the middle to second half of the tenth century used burial rites in “wooden chambers”. The change of the “ruling class” of “great mounds and boats” to a new privileged group of “wooden chambers” took place around the 940s–960s, either because the city was conquered by the troops of the Rurikid polity, or, more likely, because of an internal conflict between the two privileged groups

Magnetoelectric Effect: Principles and Applications in Biology and Medicine– a Review

Magnetoelectric (ME) effect experimentally discovered about 60 years ago remains one of the promising research fields with the main applications in microelectronics and sensors. However, its applications to biology and medicine are still in their infancy. For the diagnosis and treatment of diseases at the intracellular level, it is necessary to develop a maximally non-invasive way of local stimulation of individual neurons, navigation, and distribution of biomolecules in damaged cells with relatively high efficiency and adequate spatial and temporal resolution. Recently developed ME materials (composites), which combine elastically coupled piezoelectric (PE) and magnetostrictive (MS) phases, have been shown to yield very strong ME effects even at room temperature. This makes them a promising toolbox for solving many problems of modern medicine. The main ME materials, processing technologies, as well as most prospective biomedical applications will be overviewed, and modern trends in using ME materials for future therapies, wireless power transfer, and optogenetics will be considered. © 2021 The Author(s).This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, refs. UIDB/50011/2020 and UIDP/50011/2020, financed by national funds through the FCT/MCTES. Part of this work was funded by national funds (OE), through FCT – Fundaç~ao para a Ci^encia e a Tecnologia, I.P., in the scope of the framework contract foreseen in the numbers 4, 5, and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19. The financial support from the Ministry of Science and Higher Education of the Russian Federation is acknowledged (grant agreements №075-15-2021-588 from 1.06.2021)

Fragmentation channels of relativistic 7^7Be nuclei in peripheral interactions

Nuclei of $^7$Li were accelerated at the JINR Nuclotron. After the charge-exchange reaction involving these nuclei at an external target a second $^7$Be beam of energy 1.23A GeV was formed. This beam was used to expose photo-emulsion chambers. The mean free path for inelastic $^7$Be interactions in emulsion $\lambda$=14.0$\pm$0.8 cm coincides within the errors with those for $^6$Li and $^7$Li nuclei. More than 10% of the $^7$Be events are associated with the peripheral interactions in which the total charge of the relativistic fragments is equal to the charge of the $^7$Be and in which charged mesons are not produced. An unusual ratio of the isotopes is revealed in the composition of the doubly charged $^7$Be fragments: the number of $^3$He fragments is twice as large as that of $^4$He fragments. In 50% of peripheral interactions, a $^7$Be nucleus decays to two doubly charged fragments. The present paper gives the channels of the $^7$Be fragmentation to charged fragments. In 50% of events, the $^7$Be fragmentation proceeds only to charged fragments involving no emission of neutrons. Of them, the $^3$He+$^4$He channel dominates, the $^4$He+d+p and $^6$Li+pchannels constitute 10% each. Two events involving no emission of neutrons are registered in the 3-body $^3$He+t+p and $^3$He+d+d channels. The mean free path for the coherent dissociation of relativistic $^7$Be nuclei to $^3$He+$^4$He is 7$\pm$1 m. The particular features of the relativistic $^7$Be fragmentation in such peripheral interactions are explained by the $^3$He+$^4$He 2-cluster structure of the $^7$Be nucleus.Comment: 10 pages, 3 figures, 3 tables, conference: Conference on Physics of Fundamental Interactions, Moscow, Russia, 5-9 Dec 200