Ultrasonic investigations of spin-ices Dy2_2Ti2_2O7_7 and Ho2_2Ti2_2O7_7 in and out of equilibrium

We report ultrasound studies of spin-lattice and single-ion effects in the spin-ice materials Dy$_2$Ti$_2$O$_7$ (DTO) and Ho$_2$Ti$_2$O$_7$ (HTO) across a broad field range up to 60 T, covering phase transformations, interactions with low-energy magnetic excitations, as well as single-ion effects. In particular, a sharp dip observed in the sound attenuation in DTO at the gas-liquid transition of the magnetic monopoles is explained based on an approach involving negative relaxation processes. Furthermore, quasi-periodic peaks in the acoustic properties of DTO due to non-equilibrium processes are found to be strongly affected by {\em macroscopic} thermal-coupling conditions: the thermal runaway observed in previous studies in DTO can be suppressed altogether by immersing the sample in liquid helium. Crystal-electric-field effects having higher energy scale lead to a renormalization of the sound velocity and sound attenuation at very high magnetic fields. We analyze our observations using an approach based on an analysis of exchange-striction couplings and single-ion effects

Analysis of model predictive control through a power converter in a renewable energy system

Predictive control developments for applications in the field of renewable energy systems are still under investigation. In this article, the fundamentals of predictive control are studied with a focus on model predictive control (MPC). Based on this techniques, a control strategy for flexible power supply can be developed which could be implemented in renewable energy systems, such as solar photovoltaic (PV) systems

Low-temperature magnetism in the honeycomb systems SrLn2O4

Recent progress in the understanding of the complex magnetic properties of the family of rare-earth strontium oxides, SrLn2O4, is reviewed. These compounds consisting of hexagons and triangles are affected by geometrical frustration and therefore exhibit its characteristic features, such as a significant reduction of magnetic ordering temperatures and complex phase diagrams in an applied field. Some of the observed features appear to be rather remarkable even in the context of the unusual behavior associated with geometrically frustrated magnetic systems. Of particular interest is the coexistence at the lowest temperature of different magnetic structures (exhibiting either long or short-range order) characterized by different propagation vectors in materials without significant chemical or structural disorder.Comment: Review Articl

УДОСКОНАЛЕННЯ ІГРОВОЇ МАЙСТЕРНОСТІ КУРСАНТІВ І СТУДЕНТІВ ВІЙСЬКОВИХ НАВЧАЛЬНИХ ЗАКЛАДІВ УКРАЇНИ ЗАСОБАМИ МІНІ-ФУТБОЛУ

The use of tactical schemes of conducting two-way game of mini soccer is analyzed. Ways of improving the effectiveness of indoor soccer game while participating in competitions of various levels conducted among teams of security ministries of Lviv region and Ukraine are examined and suggested. The basic trends of improving educational and training process during training and competitive activities.Проаналізовано використання тактичних схем ведення двосторонньої гри в міні-футбол. Розглянуто та запропоновано шляхи підвищення ефективності гри в міні-футбол під час участі в змаганнях різного рівня, які проводяться серед збірних команд силових структур Львівщини та України. Виокремлено основні тенденції вдосконалення навчально-тренувального процесу під час тренування та змагальної діяльності

Alginate encapsulation to enhance biopreservation scope and success: a multidisciplinary review of current ideas and applications in cryopreservation and non-freezing storage

BACKGROUND: The development of encapsulation technologies has played an important role in improving cryopreservation outcomes for many cell and tissue types over the past 20 years. Alginate encapsulation cryopreservation (AECryo) has been incorporated into a range of applications in biotechnology, species conservation and clinical therapies, using cells from many different phyla, including higher plants, animal and human cells. This review describes the background to the origins of AECryo, the development of AECryo in higher plant tissues, broadening to current applications in algal conservation, the roles for AECryo in preserving phytodiversity, fungal species and in animal and human cells. OBJECTIVE: The main aims are to provide information resources on AECryo in different areas of biology and to stimulate new ideas for wider applications and future improvement. The translation of this useful biopreservation strategy into new opportunities for cell cryopreservation and storage at non-freezing temperatures are also discussed

Modern scaffolding strategies based on naturally pre-fabricated 3D biomaterials of poriferan origin

Modern scaffolding strategies include two key ways: to produce requested 3D constructs from corresponding precursors using technological tools, or simply use naturally already pre-fabricated scaffolds if they originate from renewable sources. Marine sponges inhabit oceans since the Precambrian. These ancient multicellular organisms possess a broad variety of evolutionary approved and ready to use skeletal structures, which seem to be well applicable as 3D scaffolds in diverse fields of modern bioinspired materials science, biomimetics and regenerative medicine. In this review, most attention is paid to biosilica-, chitin-, and spongin-based scaffolds of poriferan origin with respect to their potential use. © 2020, The Author(s).Deutsche Forschungsgemeinschaft, DFG: HE 394–3Ministerstwo Nauki i Szkolnictwa Wyższego, MNiSW: 0912/SBAD/2006PPN/BEK/2018/1/00071Deutsche Forschungsgemeinschaft, DFGSächsisches Staatsministerium für Wissenschaft und Kunst, SMWK: 02010311This work was financially supported by German Research Foundation (DFG) grant HE 394–3, SMWK Project 02010311 (Germany) and subsidy from the Ministry of Science and Higher Education, Poland to PUT (no. 0912/SBAD/2006). M.W. is thankful for financial support from Polish National Agency for Academic Exchange (PPN/BEK/2018/1/00071)

Thermodynamic Study of Excitations in a 3D Spin Liquid

In order to characterize thermal excitations in a frustrated spin liquid, we have examined the magnetothermodynamics of a model geometrically frustrated magnet. Our data demonstrate a crossover in the nature of the spin excitations between the spin liquid phase and the high-temperature paramagnetic state. The temperature dependence of both the specific heat and magnetization in the spin liquid phase can be fit within a simple model which assumes that the spin excitations have a gapped quadratic dispersion relation.Comment: 5 figure

ХАРАКТЕРИСТИКА РІВНЯ ФІЗИЧНОЇ ПІДГОТОВЛЕНОСТІ АБІТУРІЄНТІВ ЛЬВІВСЬКОГО ДЕРЖАВНОГО УНІВЕРСИТЕТУ БЕЗПЕКИ ЖИТТЄДІЯЛЬНОСТІ

The article is an assessment of the level of physical training of students of the Lviv State University of Life Safety of the 2010 entrance campaign. According to the results of tests the main indicators of the development of basic physical qualities, such as strength, speed, endurance, were determined. The curriculum of physical training at the LSU LS should be reviewed basing on the obtained results.У статті здійснюється оцінка рівня фізичної підготовленості абітурієнтів Львівського державного університету безпеки життєдіяльності набору 2010 року. За результатами тестувань визначено основні показники розвитку основних фізичних якостей: сили, швидкості, витривалості. На підставі отриманих результатів слід переглянути зміст навчальної програми з фізичного виховання ЛДУ БЖД

Chaotic Phenomenon in Nonlinear Gyrotropic Medium

Nonlinear gyrotropic medium is a medium, whose natural optical activity depends on the intensity of the incident light wave. The Kuhn's model is used to study nonlinear gyrotropic medium with great success. The Kuhn's model presents itself a model of nonlinear coupled oscillators. This article is devoted to the study of the Kuhn's nonlinear model. In the first paragraph of the paper we study classical dynamics in case of weak as well as strong nonlinearity. In case of week nonlinearity we have obtained the analytical solutions, which are in good agreement with the numerical solutions. In case of strong nonlinearity we have determined the values of those parameters for which chaos is formed in the system under study. The second paragraph of the paper refers to the question of the Kuhn's model integrability. It is shown, that at the certain values of the interaction potential this model is exactly integrable and under certain conditions it is reduced to so-called universal Hamiltonian. The third paragraph of the paper is devoted to quantum-mechanical consideration. It shows the possibility of stochastic absorption of external field energy by nonlinear gyrotropic medium. The last forth paragraph of the paper is devoted to generalization of the Kuhn's model for infinite chain of interacting oscillators