Anisotropic Exchange in LiCuVO4_4 probed by ESR

We investigated the paramagnetic resonance in single crystals of LiCuVO$_4$ with special attention to the angular variation of the absorption spectrum. To explain the large resonance linewidth of the order of 1 kOe, we analyzed the anisotropic exchange interaction in the chains of edge-sharing CuO$_6$ octahedra, taking into account the ring-exchange geometry of the nearest-neighbor coupling via two symmetric rectangular Cu-O bonds. The exchange parameters, which can be estimated from theoretical considerations, nicely agree with the parameters obtained from the angular dependence of the linewidth. The anisotropy of this magnetic ring exchange is found to be much larger than it is usually expected from conventional estimations which neglect the bonding geometry. Hence, the data yield the evidence that in copper oxides with edge-sharing structures the role of the orbital degrees of freedom is strongly enhanced. These findings establish LiCuVO$_4$ as one-dimensional compound at high temperatures. PACS: 76.30.-v, 76.30.Fc, 75.30.EtComment: 18 pages, 6 figure

“LITERARY LIVING ROOM” AS A FORM OF WORK ON THE HARMONIZATION OF FAMILY RELATIONSHIPS

The article substantiates the need to create conditions for the development of higher mental functions, emotional and volitional sphere, creative potential of preschoolers, and correction of child-parent relations. One of the forms of interaction between teachers and parents of preschool children is presented. The conclusion is made about the need for psychological and pedagogical support, the formation of students’ reading taste, the development of speech.В статье обоснована необходимость создания условий для развития высших психических функций, эмоционально-волевой сферы, творческого потенциала дошкольников, коррекции детско-родительских отношений.Представлена одна из форм взаимодействия педагогов и родителей детей дошкольного возраста. Сделан вывод о необходимости психолого- педагогического сопровождения, формирования у воспитанников читательского вкуса, развития речи

Pedagogical dialogue: cognitive strategies of philological education in Russia and abroad

The article presents an overview of an International scientific and pedagogical forum "The Image of Russia in global educational space: language, history, culture", which was held on May 23-26 2019 at Ural State Pedagogical University (Russia, Yekaterinburg) and Jilin University of international studies (China, Changchun).В статье представлен обзор Международного научно-педагогического форума "Образ России в глобальном образовательном пространстве: язык, история, культура", который был проведен с 23 по 26 мая 2019 года в Уральском государственном педагогическом университете (Россия, Екатеринбург) и Цзилиньском университете международных исследований (Китай, Чанчунь)

Electron spin resonance and exchange paths in the orthorhombic dimer system Sr2VO4

We report on magnetization and electron spin resonance (ESR) measurements of Sr$_{2}$VO$_4$ with orthorhombic symmetry. In this dimer system the $V^{4+}$ ions are in tetrahedral environment and are coupled by an antiferromagnetic intra-dimer exchange constant $J/k_B \approx$ 100 K to form a singlet ground state without any phase transitions between room temperature and 2 K. Based on an extended-H\"{u}ckel-Tight-Binding analysis we identify the strongest exchange interaction to occur between two inequivalent vanadium sites via two intermediate oxygen ions. The ESR absorption spectra can be well described by a single Lorentzian line with an effective g-factor $g$ = 1.89. The temperature dependence of the ESR intensity is well described by a dimer model in agreement with the magnetization data. The temperature dependence of the ESR linewidth can be modeled by a superposition of a linear increase with temperature with a slope $\alpha$ = 1.35 Oe/K and a thermally activated behavior with an activation energy $\Delta/k_B$ = 1418 K, both of which point to spin-phonon coupling as the dominant relaxation mechanism in this compound.Comment: 5 pages, 4 figure

NEW APPROACHES TO THE ORGANIZATION OF SKIN CANCER SCREENING

Skin cancer is the most common type of cancer in the Russian Federation. Despite the high incidence rate of skin cancer, there is no single standard for screening to identify this disease at an early stage, therefore, screening programs for detecting premalignant lesions and skin cancer at early stages are of great importance. The article describes the results of the action dedicated to the World Day against melanoma, held in Krasnoyarsk Regional Clinical Oncology Center named after A.I. Kryzhanovsky. Selection of participants was based on electronic applications, including photographs of skin lesions taken by the patients themselves. Out of the 343 people who applied, 143 (41.7 %) persons were selected for physician’s consultation. There were revealed 6 cases of melanoma, 13 basal cell tumors, and 1 lymphoproliferative disorders of the skin

Technologies of distant education at the chemistry department of Moscow State University by M. V. Lomonosov. Development dynamics

В работе представлены результаты и опыт внедрения дистанционных образовательных технологий в учебный процесс на химическом факультете МГУ имени М. В. Ломоносова.This work presents the results and experience of introduction of distant education technologies at the Chemistry Department of M. V. Lomonosov Moscow State University

Structural and magnetic dimers in the spin-gapped system CuTe2O5

We investigated the magnetic properties of the system CuTe2O5 by susceptibility and electron spin resonance measurements. The anisotropy of the effective g-factors and the ESR linewidth indicates that the anticipated structural dimer does not correspond to the singlet-forming magnetic dimer. Moreover, the spin susceptibility of CuTe2O5 can only be described by taking into account interdimer interactions of the same order of magnitude than the intradimer coupling. Analyzing the exchange couplings in the system we identify the strongest magnetic coupling between two Cu ions to be mediated by super-super exchange interaction via a bridging Te ligand, while the superexchange coupling between the Cu ions of the structural dimer only results in the second strongest coupling

Remote monitoring of adolescents with type 1 diabetes mellitus using a mobile application

Background: The prevalence of type 1 diabetes mellitus (T1DM) in childhood is increasing every year. Adolescence is the most challenging age for achieving optimal metabolic control of T1DM. Telemedicine has already been shown to be ­effective in children with the condition, but there are not enough studies in adolescents. The use of mobile apps may be associated with better glycemic control in patients with type 1 diabetes.Aims: To assess the effectiveness and safety of a model of medical care for adolescents with type 1 diabetes using remote counseling and a mobile application.Materials and methods: Were included adolescents aged ≥14 and 18 years with a T1DM duration> 3 months, a glycated hemoglobin level (HbA1c)> 7%. The duration of the study was 26 weeks. There were 3 face-to-face and at least 4 remote visits using a mobile application. All patients underwent standard examination and anthropometry, study of HbA1c, registration and analysis of indicators, assessment and correction of the treatment. The quality of life of adolescents was assessed at baseline and at the end of the study. Adolescents and physicians were interviewed about program evaluation.Results: 56 patients were included, 7 adolescents withdrew. HbA1c significantly decreased by the 12th week of the study (–0.3%; p = 0.005), by the end of the study the change in HbA1c was –0.5% (p <0.001). There was an increase in the percentage of glucose measurements in the target range (+5.3 pp; p = 0.016) and a decrease in blood glucose variability (-3.1 pp; p =  0.015). There was a significant improvement in both the total assessment of the quality of life by patients (+2.9 points; p = 0.008) and individual components of its indicators: attitude to diabetes (+3.0 points; p = 0.049), attitude to treatment (+4.6 points; p = 0.010) and communication with others (+4.5 points; p = 0.015). The majority of doctors and patients assessed their participation in the study positively. The incidence of adverse events did not change significantly during the study from baseline.Conclusion: Remote counseling using a mobile app is a safe and effective approach for adolescents with T1DM in terms of glycemic control and quality of life, and provides convenience and speed of interaction

Optical study of phonons and electronic excitations in tetragonal Sr2_2VO4_4

We report on the optical excitation spectra in Sr$_2$VO$_4$. The phonon modes are assigned and their evolution with temperature is discussed in the frame of the different phase transitions crossed upon cooling. Besides the expected infrared-active phonons we observe two additional excitations at about 290 cm$^{-1}$ and 840 cm$^{-1}$ which could correspond to electronic transitions of the V$^{4+}$ ions. Our experimental results are discussed in the context of recent experimental and theoretical studies of this material with a unique spin-orbital ground state.Comment: 7 pages, 6 figure