Investigation of the thermal expansion and heat capacity of the CaCu3Ti4O12 ceramics

The thermal expansion of the CaCu3Ti4O12 ceramics has been measured over a wide temperature range 120–1200 K. The high quality of the samples under study has been confirmed by good agreement of the results of measurements of the heat capacity in the range 2–300 K and in the vicinity of the phase transition of magnetic nature at 25 K with the data for the single crystal. No anomalies in the thermal expansion that can be associated with the phase transition at 726–732 K assumed by other investigators have been found. The influence exerted on the thermal expansion by the heat treatment of the sample in a helium atmosphere and in air has been investigated

Spin state crossover in Co3BO5

We have investigated the spin and oxidation states of Co in Co3BO5 using x-ray magnetic circular dichroism (XMCD) and dc magnetic susceptibility measurements. At low temperatures, XMCD experiments have been performed at the Co K-edge in Co3BO5 and Co2FeBO5 single crystals in the fully ferrimagnetically ordered phase. The Co (K-edge) XMCD signal is found to be related to the Co2+ magnetic sublattices in both compounds, providing strong experimental support for the low-spin (LS) Co3+ scenario. The paramagnetic susceptibility is highly anisotropic. An estimation of the effective magnetic moment in the temperature range 100-250 K correlates well with two Co2+ ions in the high-spin (HS) state and some orbital contribution, while Co3+ remains in the LS state. The crystal structure of the Co3BO5 single crystal has been solved in detail at the T range 296-703 K. The unit cell parameters and volume show anomalies at 500 and 700 K. The octahedral environment of the Co4 site strongly changes with heating. The generalized gradient approximation with Hubbard U correction calculations have revealed that, at low-temperatures, the system is insulating with a band gap of 1.4 eV, and the Co2+ ions are in the HS state, while Co3+ are in the LS state. At high temperatures (T > 700 K), the charge ordering disappears, and the system becomes metallic with all Co ions in 3d7 electronic configuration and HS state. © 2021 American Physical Society.We acknowledge many inspirational discussions on the topic of this paper with the late Natalia Ivanova and Leonard Bezmaternykh. The authors acknowledge A. Ney for allowing us to use the XANES spectrum of film. We are grateful to the Russian Foundation for Basic Research (Project No. 20-02-00559) and President Council on Grants (Project No. МК-2339.2020.2) for supporting this paper. This paper was carried out within the state assignment of the Russian Ministry of Science and High Education via program “Quantum”' (No. AAAA-A18-118020190095-4). We also acknowledge support by Russian Ministry of Education and Science via Contract No. 02.A03.21.0006. We acknowledge financial support from the Spanish Ministry of Economy, Industry and Competitiveness (MINECO, Grant No. MAT2017-83468-R) and from the regional Government of Aragon (E12-20R RASMIA project)

Dielectric relaxation and phase transition behavior of (1–x)Pb(Zn1/3Nb2/3)O3-xBaTiO3 binary solid solutions

Dielectric relaxation and phase transition behaviors in (1–x)Pb(Zn1/3Nb2/3)O3-xBaTiO3 (PZN-BT) binary solid solutions have been systematically studied in this paper. All the compositions display a pure pseudo-cubic perovskite structure. As the BT contents increase from 10 mol% to 70 mol%, the phase transition peak becomes broader and broader, accompanying with decreases of ɛm (the maximum dielectric permittivity) and Tm (the temperature corresponds to the ɛm). Nevertheless, an abnormal increase of ɛm and Tm occurs when the BT contents exceeds 70 mol%, forming a “U” shaped curve of the compositional dependence of ɛm and Tm. Moreover, it is indicated from the new glass model fitting results that the characteristic parameter p, which represents the degree of relaxation, also shows a similar “U” shaped variation curve. Similarly, as shown in polarization-electric field loops, both remnant polarizations (Pr) and coercive fields (Ec) display the “U” shaped curve as the BT content changes from 10 mol% to 80 mol%. Finally, according to the similar variation of these key parameters mentioned above, a polarization mismatched model, which describes the destruction and reestablishment of the long range order arrangement in solid solutions composed of two kinds of ferroelectrics, is proposed to illustrate the underlying mechanism. In this PZN-BT system or other similar ABO3-type perovskite relaxors, the competition between the A-O and B-O coupling plays an important role to form the “U” shaped evolution of these key parameters. © 201

2020 Clinical guidelines for Atrial fibrillation and atrial flutter

Russian Society of Cardiology (RSC).With the participation of Russian Scientific Society of Clinical Electrophysiology, Arrhythmology and Cardiac Pacing, Russian Association of Cardiovascular Surgeons.Approved by the Scientific and Practical Council of the Russian Ministry of Health

Safety and immunogenicity of rAd26 and rAd5 vector-based heterologous prime-boost COVID-19 vaccine against SARS-CoV-2 in healthy adolescents: an open-label, non-randomized, multicenter, phase 1/2, dose-escalation study

To protect young individuals against SARS-CoV-2 infection, we conducted an open-label, prospective, non-randomised dose-escalation Phase 1/2 clinical trial to evaluate the immunogenicity and safety of the prime-boost “Sputnik V” vaccine administered at 1/10 and 1/5 doses to adolescents aged 12–17 years. The study began with the vaccination of the older cohort (15-to-17-year-old participants) with the lower (1/10) dose of vaccine and then expanded to the whole group (12-to-17-year-old participants). Next, 1/5 dose was used according to the same scheme. Both doses were well tolerated by all age groups. No serious or severe adverse events were detected. Most of the solicited adverse reactions were mild. No significant differences in total frequencies of adverse events were registered between low and high doses in age-pooled groups (69.6% versus 66.7%). In contrast, the 1/5 dose induced significantly higher humoral and T cell-mediated immune responses than the 1/10 dose. The 1/5 vaccine dose elicited higher antigen-binding (both S and RBD-specific) as well as virus-neutralising antibody titres at the maximum of response (day 42), also resulting in a statistically significant difference at a distanced timepoint (day 180) compared to the 1/10 vaccine dose. Higher dose resulted in increased cross-neutralization of Delta and Omicron variants.;Clinical Trial RegistrationClinicalTrials.gov, NCT04954092, LP-007632

Трудности диагностики детского мультисистемного воспалительного синдрома, ассоциированного с COVID-19, в сочетании с ранней стадией первичной инфекции, вызванной вирусом Эпштейна-Барр

Multisystem inflammatory syndrome in children (MIS-C) associated with COVID-19 is a rare life-threatening immunopathological complication of COVID-19 that develops 1-6 weeks after the acute coronavirus infection. MIS-C is characterized by fever and multiorgan inflammation.We present a clinical case of a 10-year-old boy with skin lesions at the onset of MIS-C (erythematous malar rash, lacelike rash on the trunk and extremities and petechiae) with macrophage activation syndrome development and the early stage of primary Epstein-Barr virus infection (EBV infection) which required the exclusion of X-linked lymphoproliferative disease.This clinical case demonstrates the complexity of diagnosis in MIS-C with skin manifestations at the onset of the disease, especially with concurrent activation of other infections, particularly EBV infection.Детский мультисистемный воспалительный синдром (ДМВС), ассоциированный с COVID-19 — это редкое жизнеугрожающее иммунопатологическое осложнение, развивающееся через 1-6 недель после перенесенной новой коронавирусной инфекции, протекающее с лихорадкой и мультиорганным воспалением.В статье представлено клиническое наблюдение мальчика в возрасте 10 лет с поражением кожи в дебюте ДМВС в виде полиморфной сыпи (эритема на щеках, сыпь в виде кружевного рисунка на туловище и конечностях, петехии), с одновременным обнаружением маркеров ранней стадии первичной инфекции, вызванной вирусом Эпштейна-Барр (ЭБВ), а также развитием гемофагоцитарного синдрома, что потребовало исключения Х-сцепленного лимфопролиферативного синдрома.Данное клиническое наблюдение демонстрирует сложность диагностического поиска при кожных проявлениях в дебюте ДМВС, а также возможность сочетания ДМВС с другими инфекциями, в частности с ЭБВ-инфекцией