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

Relevant Aspects of Standardisation of Plant Raw Materials and Herbal Medicinal Products Containing Phenolic Compounds

Currently experts are actively working on Russian specifications for herbal drugs, herbal drug preparations, and herbal medicinal products, and specifically on analytical procedures to evaluate the quality of these medicines. The aim of this study was to provide a scientific basis for improving the procedures of qualitative and quantitative analysis of herbal drugs, herbal drug preparations and herbal medicinal products containing phenolic compounds. It was shown that the chemical nature, physicochemical and spectral characteristics of biologically active compounds should be considered a basis for the development of new methodological approaches to standardisation of plant raw materials and herbal medicines. The study used an example of herbal drugs and herbal medicinal products containing flavonoids, phenylpropanoids, and anthracene derivatives to justify the feasibility of standardisation using TLC, HPLC, spectrophotometry, as well as indicative reference standards as criteria of identity and quality. The study substantiated the necessity of a state system for development and registration of reference standards for pharmacopoeial analyses

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

On the nonlinear NMR and magnon BEC in antiferromagnetic materials with coupled electron-nuclear spin precession

We present a new study of nonlinear NMR and Bose-Einstein Condensation (BEC) of nuclear spin waves in antiferromagnetic MnCO3 with coupled electron and nuclear spins. In particular, we show that the observed behaviour of NMR signals strongly contradicts the conventional description of paramagnetic ensembles of noninteracting spins based on the phenomenological Bloch equations. We present a new theoretical description of the coupled electron-nuclear spin precession, which takes into account an indirect relaxation of nuclear spins via the electron subsystem. We show that the magnitude of the nuclear magnetization is conserved for arbitrary large excitation powers, which is drastically different from the conventional heating scenario derived from the Bloch equations. This provides strong evidence that the coherent precession of macroscopic nuclear magnetization observed experimentally can be identified with BEC of nuclear spin waves with k=0.Comment: 12 pages, 8 figure

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

Relevant Issues of Standardisation of Herbal Drugs and Herbal Drug Preparations Containing Essential Oils Samara State Medical University

Essential oils are a common group of bioactive compounds, yet their standardisation remains relevant.The aim of the study was to compare pharmacopoeial approaches to the standardisation of herbal drugs and herbal drug preparations containing essential oils using the examples of the State Pharmacopoeia of the Russian Federation (14th edition) and the European Pharmacopoeia (10th edition).The advantages of Russian pharmacopoeial approaches include testing for additional groups of bioactive compounds that contribute significantly to the pharmacotherapeutic effect of extractive preparations. The main compendial method for the component analysis of essential oils is gas chromatography with a flame ionisation detector; its limitations include the need for a considerable number of reference standards. The essential oil content limits established by the two pharmacopoeias for the same types of herbal drugs are not the same. The differences may be associated with differences in sample preparation conditions and analytical procedures for the determination of essential oil content, as well as with growth conditions of plants used to obtain data sets for the standardisation of this quality attribute. As a particular medicinal plant may have several chemotypes differing in the essential oil composition, it seems relevant to consider this composition in the studies of pharmacological activity of herbal drugs associated with essential oils

Актуальные аспекты стандартизации сырья и препаратов, содержащих фенольные соединения

Currently experts are actively working on Russian specifications for herbal drugs, herbal drug preparations, and herbal medicinal products, and specifically on analytical procedures to evaluate the quality of these medicines. The aim of this study was to provide a scientific basis for improving the procedures of qualitative and quantitative analysis of herbal drugs, herbal drug preparations and herbal medicinal products containing phenolic compounds. It was shown that the chemical nature, physicochemical and spectral characteristics of biologically active compounds should be considered a basis for the development of new methodological approaches to standardisation of plant raw materials and herbal medicines. The study used an example of herbal drugs and herbal medicinal products containing flavonoids, phenylpropanoids, and anthracene derivatives to justify the feasibility of standardisation using TLC, HPLC, spectrophotometry, as well as indicative reference standards as criteria of identity and quality. The study substantiated the necessity of a state system for development and registration of reference standards for pharmacopoeial analyses.В настоящее время в Российской Федерации продолжается работа по созданию нормативной документации на лекарственное растительное сырье, фармацевтические субстанции растительного происхождения и лекарственные препараты на основе субстанций растительного происхождения, в том числе разработка методик оценки их качества. Цель работы — научное обоснование путей совершенствования методик качественного и количественного анализа лекарственного растительного сырья и лекарственных растительных препаратов, содержащих фенольные соединения. Показано, что химическая природа биологически активных соединений, их физико-химические и спектральные характеристики должны рассматриваться как методологическая основа разработки подходов к стандартизации лекарственного растительного сырья и лекарственных растительных препаратов. На примере лекарственного растительного сырья и препаратов на его основе, содержащих флавоноиды, фенилпропаноиды и антраценпроизводные, продемонстрирована целесообразность стандартизации лекарственного растительного сырья и лекарственных растительных средств с использованием методов тонкослойной хроматографии, высокоэффективной жидкостной хроматографии, спектрофотометрии и диагностически значимых стандартных образцов в качестве критерия подлинности и качества. Обоснована необходимость создания государственной системы разработки и регистрации стандартных образцов, используемых в фармакопейном анализе

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

Crystal field of Yb3+ tetragonal centers in the YbRh 2Si2 intermetallic compound

The spectra of electron paramagnetic resonance and inelastic neutron scattering in crystals of the heavy-fermion intermetallic compound YbRh 2Si2 are interpreted. The phenomenological potentials of the crystal electric field of Yb3+ tetragonal centers and the parameter of the Hamiltonian for the spin-orbit interaction of electrons are determined from the experimental energy level schemes. A comparison of the results obtained from experimental data on electron paramagnetic resonance, inelastic neutron scattering, and Mössbauer spectroscopy shows that the most probable ground state of Yb3+ ions in the YbRh 2Si2 crystal is the Kramers doublet Γ t6 - . © 2007 Pleiades Publishing, Ltd