Hydrogen isotope exchange in proton-conducting oxides during proton and deuteron irradiation

It has been found that during accelerator beam deuteron irradiation of a proton-conducting oxide containing protium H/D isotope exchange between beam ions and dissolved ions takes place. This isotope exchange was also observed during high-energy proton irradiation of the oxide containing dissolved deuterium atoms. These results provide evidence to a new type of hydrogen isotope exchange. Any appreciable effects of conjugate diffusion of hydrogen and oxygen ions and of the interface processes on the isotope exchange rate were eliminated. In this type of exchange the rate of replacement of H+ by D+ and of D+ by H+ was determined only by the properties of the crystal. The discovered effect was used in our study to obtain experimental data characterizing the dynamic and equilibrium behavior of hydrogen isotopes in the oxide BaZr0.9Y0.1O3 - δ. © 2013 Pleiades Publishing, Ltd

Debye Temperature and Quantum Diffusion of Hydrogen in Body-Centered Cubic Metals

Diffusion of deuterium in potassium is studied herein. Mass transfer is controlled predominantly by the mechanism of overbarrier atomic jumps at temperatures 120-260 K and by the tunneling mechanism at 90-120 K. These results together with literature data allowed us to determine conditions under which the quantum diffusion of hydrogen in metals can be observed, which is a fundamental problem. It is established that in metals with a body-centered cubic lattice tunneling can be observed only at temperatures below the Debye temperature θD solely for metals with θD < 350 K. Predictions are made for metals in which quantum diffusion of hydrogen can be experimentally registered. Metals for which such results cannot be obtained are specified as well. Among them are important engineering materials such as α-Fe, W, Mo, V, and Cr. © 2022 The Authors. Published by American Chemical Society.Ministry of Education and Science of the Russian Federation, Minobrnauka: AAAA-A19-119012990095-0The research was carried out within the state assignment of Ministry of Science and Higher Education of the Russian Federation (theme “Function” no. AAAA-A19-119012990095-0)

Analysis of doctors’ appeals on the issues of countering doping in sports

Objective: the main topics of the doctors’ questions were the preparation of medical documents for a TUE application, the determination of the anti­doping status of various substances and methods, as well as the use of dietary supplements in sports.Materials and methods: an analysis was carried out of more than 400 appeals of doctors providing medical assistance to athletes of various levels on the issues of countering doping in sports. The aim of the work was to identify ways to improve educational and informational activities aimed at improving the quality of medical documents for TUE applications.Results: the need for continuous work to improve the level of doctors’ knowledge in countering doping in sports was confirmed, including clarification of the procedure for using documents from anti­doping organizations, the need to use TUE guidelines for physicians and the specifics of prescribing substances prohibited only during the competitive period

Synthesis, Structure and Electrical Properties of Li+-doped Pyrochlore Gd2Zr2O7

Received: 08.04.2020. Accepted: 20.05.2020. Published: 30.06.2020.The pyrochlore Gd1.55Li0.45Zr2O6.55 was prepared by the solution and solidstate methods. The introduction of lithium in the Gd-sublattice led to decrease in the lattice parameter a = 10.4830(8) Å in comparison with Gd2Zr2O7 (a =10.5346(2) Å). Monitoring of the lithium content in the sample during heat treatments showed a loss of lithium at temperatures above 1100 °C, so, to maintain the stoichiometry of lithium the low temperature sintering methods are required. The sample Gd1.55Li0.45Zr2O6.55 exhibited a predominant oxygen-ion transport over a wide range of temperatures. Although doping did not lead to an increase in the oxygen-ion conductivity compared to Gd2Zr2O7, it caused the suppression of the hole conductivity.The reported study was funded by RFBR and Sverdlovsk region, project number 20‑43‑660033a

Electrical Properties of Li+-Substituted Solid Solutions Based on Gd2Zr2O7

Abstract: Solid solution (Formula presented.) with a pyrochlore structure is synthesized for the first time. The cationic composition is confirmed via chemical analysis and nuclear reactions. It is found that the stoichiometry with respect to lithium is retained up to 1100°C. The lattice parameter diminishes in the homogeneity range 0 ≤ x ≤ 0.30, while the free volume of migration grows. Introducing lithium into the Gd sublattice raises oxygen–ion conductivity, due to the emergence of oxygen vacancies and enhancement of their mobility. Maximum conductivity is reached for composition with х = 0.10 (~1 × 10−3 Ω−1 cm−1, 650°C). An assumption is made about the formation of associates of the type (Formula presented.) at high contents of the dopant (x = 0.30), accompanied by an increase in the activation energy of conductivity. © 2021, The Author(s).This work was performed with a grant from the Russian Foundation for Basic Research, project no. 20-43-660033, and financial support from the State Atomic Energy Corporation ROSATOM (State Contract no. Н.4о.241.19.21.1070 of April 16, 2021; electronic identifier 07731000003210000330001)

Распространенность гиперурикемии у профессиональных спортсменов и ее роль в генезе различных патологических состояний и обменных нарушений

In recent decades, the prevalence of hyperuricemia (HU) is increasing worldwide; the role of uric acid (UA) in the genesis of various metabolic disorders, cardiovascular diseases, and kidney disease is being discussed. There are very few investigations of the rate of HU and its role in the development of diseases in certain social groups, including in professional athletes.Objective: to estimate the prevalence of HU and its role in the genesis of various pathological conditions and metabolic disturbances in professional athletes.Patients and methods. A retrospective comparative one-stage study was conducted, for which 2148 athletes who met inclusion criteria were selected and examined in the Federal Research and Clinical Center for Sports Medicine and Rehabilitation, Federal Biomedical Agency, in 2015. A control group consisted of 99 ageand sex-matched healthy volunteers examined at the V.A. Nasonova Research Institute of Rheumatology in 2017. The analysis included a comparison of the rate of HU and other examined parameters in professional athletes and healthy volunteers. The examined parameters were separately compared in athletes with/without HU, followed by statistical processing of results.Results. HU was detected in 306 (14.2%) of the 2148 athletes, more often in men (n=253 (20%) than in women (n=53 (6%); (p&lt;0.001). The rate of HU in the athletes was comparable with that in the healthy population (12.1%). The athletes with HU (n=306) compared with the other athletes (n=1842) had the following statistically higher indicators: the mean serum levels of creatinine, triglycerides, aspartate aminotransferase, alanine aminotransferase, gamma-glutamyltranspeptidase, creatinine phosphokinase, and myoglobin, glomerular filtration rate, and body mass index (BMI) (p&lt;0.00001 for all cases).Conclusion. HU is detected quite often in professional athletes (14.2%), which is comparable with the indicators seen in healthy volunteers (12.1%). The high prevalence of HU and its association with indicators reflecting kidney function, lipid metabolic disturbances, and BMI necessitate further investigations aimed at searching the causes of HU and methods of its prevention and treatment in professional athletes.В последние десятилетия распространенность гиперурикемии (ГУ) в мире увеличивается, обсуждается роль мочевой кислоты (МК) в генезе различных обменных нарушений, сердечно-сосудистых заболеваний, болезней почек. Исследований, посвященных изучению частоты ГУ и ее роли в развитии заболеваний в отдельных социальных группах, в том числе у профессиональных спортсменов, крайне мало.Цель исследования – оценка распространенности ГУ и ее роли в генезе различных патологических состояний, обменных нарушений у профессиональных спортсменов.Пациенты и методы. Проведено ретроспективное сравнительное одномоментное исследование, для участия в котором отобраны 2148 спортсменов, соответствующих критериям включения, обследованных на базе ФГБУ «Федеральный научно-клинический центр спортивной медицины и реабилитации Федерального медико-биологического агентства» в 2015 г. Группу контроля составили 99 здоровых добровольцев, сопоставимых по возрасту и полу, обследованных на базе ФГБНУ НИИР им. В.А. Насоновой в 2017 г. Анализ включал сравнение частоты ГУ и других исследуемых параметров у профессиональных спортсменов и здоровых добровольцев. Отдельно проводилось сопоставление исследуемых показателей у спортсменов с/без ГУ с последующей статистической обработкой результатов.Результаты. ГУ выявлена у 306 (14,2%) из 2148 спортсменов, чаще у мужчин (253, или 20%), чем у женщин (53, или 6%; p&lt;0,001). Частота ГУ у спортсменов оказалась сопоставимой с таковой в здоровой популяции (12,1%). У спортсменов с ГУ (n=306) в сравнении с остальными спортсменами (n=1842) статистически выше были следующие показатели: средние сывороточные уровни креатинина, триглицеридов, а также аспартатаминотрансферазы, аланинаминотрансферазы, гамма-глутамилтранспептидазы, креатининфосфокиназы, миоглобина, скорости клубочковой фильтрации, индекса массы тела (ИМТ; р&lt;0,00001 для всех случаев).Выводы. ГУ у профессиональных спортсменов выявляется достаточно часто (14,2%), что сопоставимо с показателями у здоровых добровольцев (12,1%). Высокая распространенность ГУ, ассоциация ее с показателями, отражающими функцию почек, нарушениями липидного обмена, ИМТ делают необходимыми дальнейшие исследования, направленные на поиск причин, методов профилактики и лечения ГУ у профессиональных спортсменов

CVD growth of carbon nanostructures from zirconia: mechanisms and a method for enhancing yield.

By excluding metals from synthesis, growth of carbon nanostructures via unreduced oxide nanoparticle catalysts offers wide technological potential. We report new observations of the mechanisms underlying chemical vapor deposition (CVD) growth of fibrous carbon nanostructures from zirconia nanoparticles. Transmission electron microscope (TEM) observation reveals distinct differences in morphological features of carbon nanotubes and nanofibers (CNTs and CNFs) grown from zirconia nanoparticle catalysts versus typical oxide-supported metal nanoparticle catalysts. Nanofibers borne from zirconia lack an observable graphitic cage consistently found with nanotube-bearing metal nanoparticle catalysts. We observe two distinct growth modalities for zirconia: (1) turbostratic CNTs 2-3 times smaller in diameter than the nanoparticle localized at a nanoparticle corner, and (2) nonhollow CNFs with approximately the same diameter as the nanoparticle. Unlike metal nanoparticle catalysts, zirconia-based growth should proceed via surface-bound kinetics, and we propose a growth model where initiation occurs at nanoparticle corners. Utilizing these mechanistic insights, we further demonstrate that preannealing of zirconia nanoparticles with a solid-state amorphous carbon substrate enhances growth yield.This material is based upon work supported by the National Science Foundation under Grant No. 1007793 and was also supported by Airbus group, Boeing, Embraer, Lockheed Martin, Saab AB, Hexcel, and TohoTenax through MIT’s Nano- Engineered Composite aerospace STructures (NECST) Consortium. This research was supported (in part) by the U.S. Army Research Office under Contract W911NF-13-D-0001. This work was performed in part at the Center for Nanoscale Systems (CNS), a member of the National Nanotechnology Infrastructure Network (NNIN), which is supported by the National Science Foundation under NSF Award No. ECS-0335765. CNS is part of Harvard University. This work was carried out in part through the use of MIT Microsystems Technology Laboratories. Stephan Hofmann acknowledges funding from EPSRC under grant EP/H047565/1. Piran Kidambi acknowledges the Lindemann Trust Fellowship.This is the final published version. It first appeared at http://pubs.acs.org/doi/abs/10.1021/ja509872y

Isotopic exchange of gaseous oxygen with mechanoactivated manganese oxides

Isotope exchange of oxygen 18O 2 with oxides Mn 2O 3 and Mn 3O 4 was investigated in the temperature range of 300-700° C. It was established that the content of the isotope O 18 in mechanically activated powders was noticeably higher than in the initial ones. Already at relatively low annealing temperatures isotope exchange leads to nearly the maximum possible under the given conditions replacement of atoms 16O to 18O. The isotope exchange parameters connected with the processes at the boundaries of the particles of mechanoactivated powder and within their volume were determined. © (2012) Trans Tech Publications

Disks of Oxygen Vacancies on the Surface of TiO₂ Nanoparticles

Oxide nanopowders are widely used in engineering, and their properties are largely controlled by the defect structure of nanoparticles. Experimental data on the spatial distribution of defects in oxide nanoparticles are unavailable in the literature, and in the work presented, to gain such information, methods of nuclear reactions and deuterium probes were employed. The object of study was oxygen-deficient defects in TiO2 nanoparticles. Nanopowders were synthesized by the sol–gel method and laser evaporation of ceramic targets. To modify the defect structure in nanoparticles, nanopowders were subjected to vacuum annealings. It was established that in TiO2 nanoparticles there form two-dimensional defects consisting of six titanium atoms that occupy the nanoparticle surface and result in a remarkable deviation of the chemical composition from the stoichiometry. The presence of such defects was observed in two cases: in TiO2 nanoparticles alloyed with cobalt, which were synthesized by the sol–gel method, and in nonalloyed TiO2 nanoparticles synthesized by laser evaporation of ceramic target. The concentration of the defects under study can be varied in wide limits via vacuum annealings of nanopowders which can provide formation on the surface of oxide nanoparticles of a solid film of titanium atoms 1–2 monolayers in thickness