Ionospheric effects during first 2 hours after the Chelyabinsk meteorite impact

This paper presents the analysis of ionospheric effects in the region close to the Chelyabinsk meteorite explosion at 03:20UT 2013 February 15 from the Institute of Solar-Terrestrial Physics of Siberian Branch of Russian Academy of Sciences (ISTP SB RAS) EKB radar data, and from the Institute of Geophysics of Ural Branch of Russian Academy of Sciences (IG UB RAS) PARUS ionosonde data. Both instruments are located within the IG UB RAS Arti Observatory approximately 200 km northward from the estimated explosion site. According to the data obtained, the ionospheric disturbance caused by the meteorite flyby, explosion, and impact had high dynamics and amplitude. However, it obviously did not lead to a variation in the ionosphere mean parameters in the region above the disturbance center during the first 2 hours. Essential effects, however, were observed at more than 100-200 km from the explosion site and farther up to 1500 km.Comment: 30 pages, 15 figures, submitted to JAST

Superhyperfine interactions in Ce3+ doped LiYF4 crystal: ENDOR measurements

The first observation of the resolved Mims electron-nuclear double resonance (ENDOR) spectra from the nearby and remote nuclei of 19F and 7Li nuclei on impurity Ce3+ ions in LiYF4 crystal is reported. It shows that LiYF4:Ce3+ system can be exploited as a convenient matrix for performing spin manipulations and adjusting quantum computation protocols while ENDOR technique could be used for the investigation of electron-nuclear interaction with all the nuclei of the system and exploited for the electron-nuclear spin manipulations.Comment: 4 pages, 2 figures, 1 Table. Reported on Theor-2017 (Kazan, Russia) Conferenc

Новые подходы к стандартизации травы монарды дудчатой

Objectives. The Monarda fistulosa herb of the Lamiaceae family is particularly interesting among essential oils from medicinal plants that have a wide spectrum of pharmacological activities. However, information regarding some of its flavonoids, which are found in the essential oil, is controversial. Inaccuracies in identification of the chemical composition of the herb have led to several different standardization approaches, which are cumbersome. To establish a uniform classification, here, we present confirmation for new approaches for the standardization of the Monarda fistulosa herb. Methods. Silica gel column chromatography was used to extract the flavonoids. Identification was based on ultraviolet spectroscopy, nuclear magnetic resonance spectroscopy, mass spectrometry, and acidic hydrolysis. The quality of the proposed quantitation methodology for total flavonoids was assessed by differential spectrophotometry at 394 nm, in isorhoifolin equivalent.Results. We have verified new approaches for the standardization of the Monarda fistulosa herb. The approaches can determine the authenticity of the herb by detecting monoterpene phenols and flavonoids that have diagnostic value. We also developed a technique for quantitation of the total flavonoids. Conclusions. We investigated the possibility of establishing the authenticity of the Monarda fistulosa herb based on the diagnostically significant flavonoids, isorhoifolin and linarin.Цели. Среди эфиромасличных лекарственных растений, обладающих широким спектром фармакологической активности, особый интерес представляет трава монарды дудчатой (Monarda fistulosa) семейства Яснотковых. Однако информация о некоторых флавоноидах, содержащихся в ней наряду с эфирным маслом, носит противоречивый характер. Неточности, выявленные в отношении химического состава травы, становятся причиной появления различных подходов к стандартизации, что создает трудности. Для обеспечения единообразия классификации в данной работе представлено обоснование новых, ранее не применявшихся подходов к стандартизации травы монарды дудчатой. Методы. Для экстракции флавоноидов использовали колоночную хроматографию на силикагеле. Идентификацию осуществляли на основании данных ультрафиолетовой спектроскопии, спектроскопии ядерного магнитного резонанса и масс-спектрометрии, а также результатов кислотного гидролиза. Оценку качества предложенной методики количественного определения суммы флавоноидов проводили методом дифференциальной спектрофотометрии при 394 нм в пересчете на изороифолин. Результаты. Обоснованы подходы к стандартизации травы монарды дудчатой, заключающиеся в определении ее подлинности путем обнаружения монотерпеновых фенолов и флавоноидов, имеющих диагностическое значение. Разработана методика количественного определения суммы флавоноидов.Выводы. Изучена возможность определения подлинности травы монарды дудчатой, исходя из диагностически значимых флавоноидов – изороифолина и линарина

Inhomogeneity of the intrinsic magnetic field in superconducting YBa2Cu3OX compounds as revealed by rare-earth EPR-probe

X-band electron paramagnetic resonance on doped Er3+ and Yb3+ ions in Y0.99(Yb,Er)0.01Ba2Cu3OX compounds with different oxygen contents in the wide temperature range (4-120)K have been made. In the superconducting species, the strong dependencies of the linewidth and resonance line position from the sweep direction of the applied magnetic field are revealed at the temperatures significantly below TC. The possible origins of the observed hysteresis are analyzed. Applicability of the presented EPR approach to extract information about the dynamics of the flux-line lattice and critical state parameters (critical current density, magnetic penetration depth, and characteristic spatial scale of the inhomogeneity) is discussedComment: 17 pages, 5 Figures. Renewed versio

Temperature dependence of the EPR linewidth of Yb3+ - ions in Y0.99Yb0.01Ba2Cu3OX compounds: Evidence for an anomaly near TC

Electron paramagnetic resonance experiments on doped Yb3+ ions in YBaCuO compounds with different oxygen contents have been made. We have observed the strong temperature dependence of the EPR linewidth in the all investigated samples caused by the Raman processes of spin-lattice relaxation. The spin-lattice relaxation rate anomaly revealed near TC in the superconducting species can be assigned to the phonon density spectrum changesComment: 10 pages, 4 figures Renewed versio

Inhomogeneity of the intrinsic magnetic field in superconducting YBa 2Cu3OX compounds as revealed by a rare-earth EPR probe

X-band electron paramagnetic resonance experiments on doped Er 3+ and Yb3+ ions in YBa2Cu3O X (6<X<7) compounds with different oxygen contents in a wide temperature range (4-120 K) have been performed. In the superconducting species at temperatures significantly below TC, strong dependences of the linewidth and resonance line position on the sweep direction of the applied magnetic field are revealed. The possible origins of the observed hysteresis are analysed. The applicability of the presented EPR approach to extract information about the dynamics of the flux-line lattice and critical state parameters (critical current density, JC, magnetic penetration depth, λ, and characteristic spatial scale of the inhomogeneity) is discussed. © 2005 IOP Publishing Ltd

ヨーロッパの総合医制度

Coherent spin dynamics of impurity Yb3+ ions in the CaWO4 single crystal has been studied using X - and W -band EPR. Rabi oscillations of the sample magnetization with damping times comparable to their period, driven by pulses of the microwave field with duration up to 5μs, were observed. The largest value of the single-qubit figure of merit (∼6400) is obtained for the high-field component in the Y 171 b X -band EPR spectrum. The spin-lattice relaxation time of the Yb3+ ions shortens with the increasing resonance frequency while the phase memory time, in contrast, grows noticeably. Variations of the phase memory times are interpreted in terms of spectral and instantaneous diffusions. The increase of the coherence time at the W band can be used for the application of rare-earth ions as qubits in quantum computing as it has been proposed recently. © 2009 The American Physical Society

Effect of Mo3+ ions on Nd3+ spin-lattice relaxation in Y3Al5O12

The content of Mo3+ ions in YAG:Nd garnet samples prepared by different technologies has been studied, and the spin-lattice relaxation rate of these ions at temperatures of 4-5 K measured. It is concluded is drawn that Mo3+ ions can play the part of rapidly relaxing centers mediating the Nd3+ spin-lattice relaxation at liquid-helium temperatures. This may account for a number of features in the spin-lattice relaxation of rare-earth ions in garnets, observed earlier at low temperatures. © 1998 American Institute of Physics

Superhyperfine structure of the ESR spectra of Gd³⁺ impurity ions in LiYF<inf>4</inf> double fluoride

© 2017, Pleiades Publishing, Ltd.Electron spin resonance spectra of Gd3+ ions forming a small (~0.0001 at %) impurity in a LiYF4 single crystal have been investigated in a wide temperature range from liquid helium to room temperature. A number of the fine-structure components of the spectrum exhibit a pronounced superhyperfine structure depending on the orientation of the external magnetic field with respect to the crystallographic axes. The superhyperfine structure was not observed in earlier ESR studies of double fluorides with a Gd3+ impurity

Superhyperfine structure of the EPR spectra of impurity ions in the LiYF4 : Nd3+ system doped by 143Nd isotopes

© 2015, Pleiades Publishing, Ltd. Results of measuring the EPR spectra in the LiYF4: Nd3+ system doped by 143Nd isotopes with the nuclear spin I = 7/2 have been presented. We have succeeded to observe superhyperfine splitting of the EPR spectra of the samples under investigation at the orientation of the magnetic field B along the symmetry axis c of the crystal and at B ⊥ c on the lines corresponding to both even neodymium isotopes and 143Nd