Irreversibility of the magnetic state of Tm1 xTbxCo2 revealed by specific heat, electrical resistivity, and neutron diffraction measurements

The substitution of Tb for Tm in the Laves phase compound Tm Co2 leads to appearance of a magnetic moment on the Co atoms through the metamagnetic transition in the itinerant d -electron subsystem and gives rise to long-range ferrimagnetic order in Tm1-x Tbx Co2 at x≥0.15. The magnetic state of the compound Tm0.9 Tb0.1 Co2, i.e., just below the critical Tb concentration, is characterized by the presence of large regions with short-range magnetic order and localized spin fluctuations (LSFs) induced in the Co 3d -electron subsystem by the fluctuating f-d exchange due to the Tm-Tb substitution. The peculiar magnetic state of this compound is strongly influenced by an external magnetic field which produces a first-order magnetic phase transition to a long-range ferrimagnetic state with the magnetic moment on the Co atoms up to (0.7-0.8) μB. This field-induced transition in Tm0.9 Tb0.1 Co2 is found to be irreversible. It is accompanied by a giant and irreversible reduction of the electrical resistivity (Δρ ρ∼-45%), specific heat (by about 3.7 times at 2 K), and intensity of magnetic neutron scattering. Such behavior is associated with the field-induced metamagnetic transition in the itinerant d -electron subsystem mediated by the f-d exchange. Significantly enhanced values of the residual resistivity and the coefficient γ of the T -linear contribution to the specific heat in the compound with x=0.1 as well as their unusual behavior with temperature and under application of the magnetic field is ascribed to the presence of LSF. © 2006 The American Physical Society.This work was partly performed at the Swiss Spallation Neutron Source SINQ, Paul Scherrer Institute (PSI), Villigen, Switzerland. This work was supported by the Russian Foundation for Basic Research (Grant No. 04-02-96060) and by the Swiss National Science Foundation (SCOPES Project No. IB7420-110849)

Magnetic and magnetocaloric properties of (MnCo)1-xGe compounds

The crystal structure, magnetic properties, and heat capacity of the (MnCo)1-xGe compounds with x ≤ 0.05 have been studied. It was found that, as the deviation from the MnCoGe stoichiometric composition increases, the temperature of structural transition from the low-temperature phase with the orthorhombic TiNiSi-type structure to the high-temperature phase with the hexagonal Ni2In-type phase decreases rapidly, whereas the magnetic ordering temperature varies slightly. The temperature of structural transition for the composition with x = 0.02 approximately coincides with the Curie temperature of the hexagonal phase, and the transition is accompanied by a significant entropy change, namely, ΔS = 34 J/(kg K). The application of high magnetic field in the transition-temperature range causes an increase in the relative volume of the orthorhombic phase. An analysis of magnetocaloric properties of these compounds, which was performed with the formal application of the Maxwell's relationship near the temperature of first-order structural phase transition, is shown to give overestimated values of the entropy change. © Pleiades Publishing, Ltd., 2013

Doctoral Education in Ukraine: the Application of Digital Tools and Services by Doctoral Students under COVID-19 Pandemic

[EN] The paper aims to explore the peculiarities of doctoral education under COVID-19 in Ukraine. The application of digital instruments and services by doctoral students has become a priority during distance training. However, this approach is mainly a new experience and, accordingly, undergoes theoretical substantiation and piloting. The focus of the study is two-fold. It theoretically discusses the digital support of dissertation research at various stages. Secondly, based on the findings of the survey on the doctoral students application of digital tools and services the challenges have been identified. We conclude that the priority of digital education in the EU countries, especially under COVID-19 pandemic highlights the task of restructuring the doctoral education in Ukraine towards its dynamic digitalization. The digitization should be comprehensive and systematic. Systematization should include technical, organizational, motivational and developmental components aimed at synergy of institutions, doctoral students and supervisors. The complexity should include both the digitization of the training component and independent work of the doctoral students while writing a dissertation. The groups of DT&S for application by doctoral students are recommended for the inclusion into the doctoral students training curriculum both in the format of a separate course and by integration into the syllabi of other disciplines. Based on the research findings the targeted scientific/methodical events (seminars, master classes, doctoral schools, etc.) providing knowledge and skills on DT&S application are recommended.Khoruzha, L.; Lokshyna, O.; Mazur, N.; Proshkin, V. (2022). Doctoral Education in Ukraine: the Application of Digital Tools and Services by Doctoral Students under COVID-19 Pandemic. Multidisciplinary Journal for Education, Social and Technological Sciences. 9(1):87-112. https://doi.org/10.4995/muse.2022.16768OJS871129

Students' mathematical training for professional self-realization in a modern, inventive society

In the framework of their professional self-realization on the contemporary job market, the paper explores the issues with professionals' training for mathematics at universities. The structure of students' mathematical proficiency is taken into consideration, and its key elements are substantively presented (the ability to ask and answer questions in and with mathematics, the ability to deal with mathematical language and tools). The initial (ascertaining) step of the pedagogical experiment allowed for the establishment of the level of students' mathematical proficiency and formation in accordance with the predetermined structure. It has been demonstrated that students, both of mathematical and non-mathematical majors, lack the mathematical knowledge and abilities necessary to solve complicated issues, particularly those involving modeling in the context of future professional engagement. The following fundamental strategies for developing students' mathematical competence are supported: research-focused instruction, an interdisciplinary approach with a practical focus, and the use of digital learning environments and related resources. The implementation strategies for these techniques are described in the authors' optional course "Methods of formation of students' mathematical competence for the future successful career" for math specialist students. The research will continue with the introduction of the aforementioned discipline to the educational system, which will include the subsequent assessment of future teachers' readiness to employ the suggested methods in their professional work.In the framework of their professional self-realization on the contemporary job market, the paper explores the issues with professionals' training for mathematics at universities. The structure of students' mathematical proficiency is taken into consideration, and its key elements are substantively presented (the ability to ask and answer questions in and with mathematics, the ability to deal with mathematical language and tools). The initial (ascertaining) step of the pedagogical experiment allowed for the establishment of the level of students' mathematical proficiency and formation in accordance with the predetermined structure. It has been demonstrated that students, both of mathematical and non-mathematical majors, lack the mathematical knowledge and abilities necessary to solve complicated issues, particularly those involving modeling in the context of future professional engagement. The following fundamental strategies for developing students' mathematical competence are supported: research-focused instruction, an interdisciplinary approach with a practical focus, and the use of digital learning environments and related resources. The implementation strategies for these techniques are described in the authors' optional course "Methods of formation of students' mathematical competence for the future successful career" for math specialist students. The research will continue with the introduction of the aforementioned discipline to the educational system, which will include the subsequent assessment of future teachers' readiness to employ the suggested methods in their professional work

ОСВІТНІ ВЕБ-РЕСУРСИ В ПРОФЕСІЙНІЙ ПІДГОТОВЦІ МАЙБУТНІХ УЧИТЕЛІВ

In the article the important role of systemic using educational web resources in prospective teachers’ professional training is substantiated, which is a requirement of informatization of higher education and directly affects the ability and willingness of prospective teachers to use educational Web resources in their future professional activity. The author analyses the available classifications of educational web resources and presents his own classification of them according to the purpose and methods of using in the educational process of higher educational institutions. This classification consists of three main groups of Web resources: resources for students’ classroom activities (hosting for media files storage, systems of creation and storage of the training materials, systems of collective creating documents of different types etc.); resources for individual and extracurricular work of students of pedagogical universities (web resources for organizing future teachers’ project activity, distance learning systems, systems of virtual communication etc.); resources for scientific research (institutional repository, digital library, electronic periodical scientific publications, educational cloud).The author clarifies that in each specified group he pointed to the educational web resources that are the most frequently used in prospective teachers’ professional training but generally, their number is much higher. In addition, each of the named species is characterized by complex purpose and its using in the process of professional training of the teachers is not limited only by classroom, extracurricular or academic activities of the students. The author considers that this classification and methods of using educational Web resources in the educational process higher school, which are briefly characterized in the article, will produce a positive impact on the implementation of information and communication, including networking, technologies into the practice of prospective teachers’ professional training in the conditions of informatization of modern pedagogical universities educational environment.В статье обосновывается важная роль системного применения образовательных веб-ресурсов в процессе профессиональной подготовки будущих учителей, что является одним из требований информатизации высшей школы и прямо влияет на способность и желание будущих учителей применять образовательные веб-ресурсы в будущей профессиональной деятельности. Автор анализирует имеющиеся классификации образовательных веб-ресурсов и представляет собственную классификацию по назначению и методике применения в образовательном процессе вуза, которая состоит из трех основных групп веб-ресурсов: ресурсы для аудиторной работы соискателей степеней высшего образования; ресурсы для их самостоятельной и внеаудиторной работы; ресурсы для научно-исследовательской работы студентов педагогических вузов.У статті обґрунтовується важлива роль системного застосування освітніх веб-ресурсів у процесі фахової підготовки майбутніх учителів, що є однією з вимог інформатизації вищої школи і прямо впливає на здатність і бажання майбутніх учителів застосовувати освітні веб-ресурси в майбутній професійній діяльності. Автор аналізує наявні класифікації освітніх веб-ресурсів та подає власну класифікацію за призначенням та методикою застосування в освітньому процесі ВНЗ, яка складається з трьох основних груп веб-ресурсів:  ресурси для аудиторної роботи здобувачів ступенів вищої освіти; ресурси для самостійної та позааудиторної роботи студентів педагогічних вишів; ресурси для науково-дослідної роботи

The Implementation of Energy-Saving Lighting Systems for Poultry Houses

The provision of lighting in poultry shelters is an energy-intensive process in poultry farming, due to a lack of sunlight in closed facilities. Lighting plays an important role in the majority of organism biorhythms and it clocks the processes of vital activities of the birds. Lighting directly influences productivity, growth and sexual maturation of birds. A determining factor for the lifetime of an LED is the crystal heating temperature during its operation. It may be assumed that the LED lifetime is largely independent of the variation in the current passing through the LED (within the limits of its design values). The research objective was to conduct laboratory testing to compare the electricity consumption between the existing and a newly developed lighting system for poultry house no. 19 of the Kuchinsky Poultry Breeding Plant. In order to conduct the laboratory testing, the authors developed lighting fixtures consisting of sealed plastic bodies with an LED-carrying PCB inside. The testing continued for 113 days. The new system consumed 662 kWh, while the previous system consumed 783 kWh. Energy savings through the testing period amounted to 15%. During the testing, the new equipment was reliable; no failures of LED fixtures were recorded. Keywords: LED lighting, energy conservation, poultry farming, microclimat

Critical phenomena in 1D Ising model with arbitrary spin

The aim of this work was to study critical phenomena taking place in 1D Ising model with different exchange interactions signs and arbitrary spin values in a magnetic field. Exact analytical formulas for frustration fields, zero temperature magnetization and entropy at these fields are obtained. The general behavior of pair spin correlation function with the accounting of only interactions between nearest neighbors is examined. © 2018 The Authors, published by EDP Sciences.The reflorted study was carried out within the state assignment of FASO of Russia (theme «Quantum» n. 01201463332) and was funded by RFBR according to the research flroject n. 16-32-00032