Charge transfer transitions in the photoluminescence spectra of Zn1-xMexO (Me = Mn, Ni, Co) oxide compounds

Crystals of Zn1-xCoxO and Zn1-xNixO are studied by photoluminescence at temperatures of 8 and 90 K. By resolving the spectra into sums of gaussian distributions and using the known positions of donor and acceptor levels of 3d-impurities relative to the edges of the allowed bands, the observed peaks in the photoluminescence spectra are interpreted in terms of radiative recombination through donor and acceptor levels of nickel and cobalt ions. These results are compared with previously observed features of the photoluminescence spectra of Zn1-xMnxO crystals. © 2013 American Institute of Physics

Galkhaita

Los análisis de Gal-Khaya y Khaidarkan dieron, respectivamente, Hg 47,60, 49,02; Cu 3,49, 2,85; Zn 3,00, 0,60; Fe 0,31, nada ; Tl 0,46, 2,90; As 23,60, 19,49; Sb 0,59, 5,51; S 21,00, 19,31; Se 3 ppm, 150 ppm; total 100,05, 99,695 %.(...

ОПРЕДЕЛЕНИЕ МОНОЗАМЕЩЕННЫХ НИТРОФЕНОЛОВ В ВОДЕ МЕТОДОМ ГАЗОВОЙ ХРОМАТОГРАФИИ

Nitrophenols are highly toxic hydrophilic organic compounds. Nitrophenols prevalence in the biosphere is associated with both human industrial activity and with natural processes in the atmosphere and hydrosphere. Nitrophenols determination using gas chromatography requires chemical modification in order to reduce the hydrophilicity and polarity of the analytes. The derivatization must be carried out before the extraction concentration stage, but in most methods of the nitrophenols determination in water this approach is not implemented. The method of determination of mononitrophenols (2-, 3-, and 4-nitrophenols) in water was developed. It involved the nitrophenols bromination directly in the water, bromoderivatives liquid extraction with toluene, silylation by N-tert-Butyldimethylsilyl-N-methyltrifluoroacetamide (MTBSTFA) extract and gas chromatographic determination with the electron-capture detector (GC-ECD). The nitrophenols bromination conditions in aqueous solutions were optimized (pH value, bromination duration, bromide-ions concentration). In order to reduce the oxidizing activity of bromine, the nitrophenols bromination was recommended in the presence of bromide anions. The extraction (degree of extraction) and gas chromatographic (retention indices, ECD relative molar responses) properties and nitrophenols bromoderivatives properties were studied. It was shown that the degree of extraction of brominated nitrophenols in the toluene/water system exceeded 80% and the subsequent silylation of the bromoderivatives significantly improved their chromatographic properties. The analytical range of nitrophenols in water was 0.02-10 µg/dm3 with an error of 10-35%, the detection limits were 0.05-0.07 μg/dm3, the sample volume for analysis was 50 cm3, the analysis duration was 90 min.Key words: mononitrophenols, chemical modification, gas-chromatography, electron-capture detector  DOI: http://dx.doi.org/10.15826/analitika.2020.24.2.006I.V. Gruzdev, B.M. Kondratenok, E.I. Lyu-Lyan-Min Institute of Biology of Komi Scientific Centre of the Ural Branch of the Russian Academy of Sciences (IB FRC Komi SC UB RAS),Kommunisticheskaya st., 28, Syktyvkar, 167982, Russian FederationНитрофенолы – высокотоксичные гидрофильные органические соединения, распространение которых в окружающей среде связано как с промышленной деятельностью человека, так и с протеканием ряда природных процессов в атмосфере и гидросфере. При определении нитрофенолов методом газовой хроматографии требуется снижать их гидрофильность и полярность, для чего применяется химическая модификация с различными реагентами. Дериватизацию нитрофенолов необходимо проводить до стадии их экстракционного концентрирования, но в большинстве методик этот подход не реализуется. Разработан способ определения изомерных нитрофенолов (2-, 3- и 4-нитрофенол) в различных водных объектах, предполагающий получение их бромпроизводных непосредственно в воде, жидкостную экстракцию толуолом, силилирование в экстракте N-трет-бутилдиметилсилил-N-метилтрифторацетамидом (MTBSTFA) и газохроматографическое определение полученных эфирных производных с галогенселективным детектором электронного захвата (ГХ-ДЭЗ). Установлены оптимальные условия проведения бромирования нитрозамещенных фенолов в условиях водного раствора (значение рН, продолжительность бромирования, концентрация бромид-ионов). Для снижения окислительной активности брома и повышения устойчивости в растворе получаемых аналитических форм, бромирование нитрофенолов рекомендуется проводить в присутствии бромид-анионов. Изучены экстракционные (степень извлечения) и газохроматографические (индексы удерживания, относительные мольные отклики ДЭЗ) характеристики нитрофенолов и их бромсодержащих производных. Показано, что степень извлечения бромированных нитрофенолов при выбранных условиях экстракции в системе толуол/вода превышает 80 %, а последующее силилирование бромпроизводных значительно улучшает их хроматографические свойства. Интервал определяемых концентраций нитрофенолов в воде 0.2-10 мкг/дм3, пределы обнаружения 0.05-0.07 мкг/дм3, погрешность определения – 10-35 %, объем пробы – 50 см3, продолжительность анализа – 90 минут.Ключевые слова: нитрофенолы, газовая хроматография, химическая модификация, детектор электронного захватаDOI: http://dx.doi.org/10.15826/analitika.2020.24.2.00

ЭКСТРАГИРОВАНИЕ И ОПРЕДЕЛЕНИЕ ФЕНОЛА В ПОЧВЕ МЕТОДОМ ГАЗОВОЙ ХРОМАТОГРАФИИ

Existing techniques for the phenol extraction from the soil differ in the nature of the extractant mixture and in the mode of carrying out this procedure. The recommendations on the conditions for the phenol extraction are contradictory. The known techniques imply the extraction of the phenol with organic solvents, aqueous/organic, or aqueous solutions. The use of microwave or ultrasonic fields are recommended to ensure the complete extraction. However, the possibility of attaining maximum extraction of phenol without the destruction of the organic matrix of the soil has not been discussed. We have demonstrated that during phenol extraction with acidic or alkaline aqueous solutions the humic substances of the soil are destroyed. Humic substances destruction produces phenol, and thus distorts the results of the quantitative chemical analysis. The use of water/ethanol mixtures for the phenol extraction from the soil were proposed. These mixtures do not exert a harsh effect on the organic matter of the soil, while moisturizing the soil and dissolving the phenol well. The optimum conditions for the phenol extraction from the soil were established. They occurred during the extraction with a water/ethanol mixture (с(C2H5OH) = 50 % vol.) under the mechanical stirring for two hours. To increase the selectivity and sensitivity of the determination of phenol in the extract, the preliminary bromination to obtain Phenol bromoderivative (2,4,6-tribromophenol) was used with the subsequent gas chromatographic analysis with a halogen-selective electron-capture detector. A procedure was developed for the phenol determination in the soil of 0.01 to 10 mg/kg, the relative error of measurement in this range did not exceed 35%.Keywords: phenol, soil, extraction, chemical modification, gas chromatography(Russian) DOI: http://dx.doi.org/10.15826/analitika.2018.22.1.006 I.V. Gruzdev1, O.M. Zueva1, E.S. Titova1, V.V. Staliugin2, B.M. Kondratenok1 1Institute of Biology of Komi Scientific Centre of the Ural Branch of the Russian Academy of Sciences (IB Komi SC UB RAS), Kommunisticheskaya st., 28, Syktyvkar, 167982, Russian Federation2Syktyvkar State University named after Pitirim Sorokin, Petrozavodskaia st., 12, Syktyvkar, 167005, Russian FederationСуществующие подходы к экстрагированию фенола из почвы различаются природой экстрагирующей смеси и режимом проведения этой процедуры. Рекомендации по условиям экстракции фенола противоречивы, не обсуждается и возможность разрушения органического вещества почвы в процессе извлечения аналита. Показано, что при экстрагировании фенола кислыми или щелочными водными растворами, гумусовые вещества почвы деструктируют и продуцируют фенол, что приводит к существенному завышению результатов количественного химического анализа. Для экстрагирования фенола из почвы предложены водно-этанольные смеси, не оказывающие жесткого воздействия на органическое вещество почвы при сохранении хорошей смачиваемости образца и высокой растворимости фенола в экстрагенте. Установлены условия, при которых для разных типов почв достигается максимальное извлечение фенола без разрушения почвенной матрицы – экстрагирование водно-этанольной смесью (c(C2H5OH) = 50 % об.) в режиме механического перемешивания в течение двух часов. Для повышения селективности и чувствительности определения фенола в экстракте проводится получение его бромпроизводного (2,4,6-трибромфенол) и последующий газохроматографический анализ с галогенселективным детектором электронного захвата. Диапазон измерений массовой доли фенола в почве от 0.01 до 10 мг/кг, относительная погрешность измерения в этом диапазоне не превышает 35 %.Ключевые слова: фенол, почва, экстракция, химическая модификация, газовая хроматографияDOI: http://dx.doi.org/10.15826/analitika.2018.22.1.00

Automated morphometric studies of collagen fibers as an auxiliary method for diagnosing cold injury

Background. Cold injury is one of the most significant problems for the northern regions of the Russian Federation. Frostbite is defined as a complex of changes caused by the action of low temperatures, which lead to morphological changes in damaged tissue structures. As a result, the skin with underlying tissues and the intercellular matrix, the components of which are collagen fibers, are damaged, which eventually leads to remodeling and a protracted course of the wound process. Morphometric studies in combination with quantitative analysis of microphotographs (histological specimens) using GIS technologies make it possible to distinguish altered collagen fibers under the influence of low temperatures from relatively healthy tissues. The aim of the study. To assess the possibility of using computer analysis of microphotographs in  a  complex of morphometric studies of collagen fibers in local cold injury. Materials and methods. The study included 84 patients with III and IV degree frostbite of the lower extremities. Morphological study of tissues and microphotography were performed using Leica DM2500 microscope (Leica, Germany). The thickness of  collagen fibers was measured based on  visual measurements of characteristic areas of the microphotograph. Computer analysis of tissue microphotographs of  the  zone of cryoinjury was performed using the ArcINFO software (Esri, USA). Statistical processing of the study results was carried out using the SPSS Statistics software package (IBM Corp., USA). Graphs and diagrams were constructed using MS Office Excel (Microsoft Corp., USA). Results. With frostbite, severe tissue damage occurs, accompanied by the destructive processes of the extracellular matrix components. Low temperatures contribute to  changes in the width and orientation of collagen fibers in the damaged area. In  this  regard, a change in the texture of the histological specimen image leads to achange in the numerical characteristics of the standard deviation of the curvature coefficient in the studied area of the microphotograph. Thus, in the late reactive period, the described complex of morphometric studies makes it possible to classify particular microphotograph as having pathological signs or as a sample of healthy tissue

ОСОБЕННОСТИ ПРОБОПОДГОТОВКИ ПРИ ОПРЕДЕЛЕНИИ ФЕНОЛА В ВЫСОКОЦВЕТНЫХ ПРИРОДНЫХ ВОДАХ МЕТОДОМ ГАЗОВОЙ ХРОМАТОГРАФИИ

Existing the phenol determination methods in water suggest the use of extraction concentration combined with heating the sample and phenol derivatization in alkaline media. It is shown that humic substances of water samples is destructed by the alkaline solutions or heating. Humic substances destruction produces phenol and distorts the results of quantitative chemical analysis. The interfering effect of humic substances need to be eliminate in beginning of the analytical cycle. A method for removing humus by coagulation on the Al2O3 layer with simultaneous impregnation of the sorbent with copper (II) cations is proposed. The method allows to eliminate the interfering effect of humic substances in the phenol quantification in natural waters. The conditions of humic substances complete removal from the water samples is established, the role of copper (II) cations in this process is shown. Under optimal conditions, the native phenol adsorption on alumina surface does not exceed 3 %. For selective and sensitive gas-chromatographic determination of phenol in the eluate we used preliminary bromination. Phenol bromoderivative (2,4,6-tribromophenol) with a halogen-selective electron-capture detector was detected. A procedure was developed for phenol determination in water of 0.2 to 10 μg/dm3, the relative error of measurement in this range does not exceed 30 %. The water sample volume is 25 cm3, the analysis duration is 30 min.Keywords: phenol, gas chromatography, high-color natural water, chemical modification, humic substances, aluminum oxideDOI: http://dx.doi.org/10.15826/analitika.2019.23.2.004(Russian)I.V. Gruzdev, B.M. Kondratenok, O.M. Zueva, E.I. Lyu-Lyan-Min Institute of Biology of Komi Scientific Centre of the Ural Branch of the Russian Academy of Sciences (IB Komi SC UB RAS), Kommunisticheskaya st., 28, Syktyvkar, 167982, Russian FederationРяд методик определения фенольных соединений в водных средах предполагает использование в аналитическом цикле экстракционного концентрирования в сочетании с нагреванием пробы и проведение реакций дериватизации в щелочных средах. Показано, что такие операции, проводимые в присутствии гумусовых веществ, вызывают их деструкцию с образованием фенола. Предложен способ удаления гумуса путем коагуляции на слое Al2O3 при одновременном импрегнировании сорбента катионами меди (II). Способ позволяет устранить мешающее влияние гумусовых веществ при количественном определении фенола в природных водах. Установлены условия, при которых достигается полное удаление гумусовых веществ из анализируемой пробы воды, показана роль катионов меди в этом процессе. При установленных оптимальных условиях адсорбция нативного фенола на оксиде алюминия не превышает 3 %. С целью повышения чувствительности и селективности определения фенола в получаемом элюате проводится его химическая модификация в 2,4,6-трибромфенол с последующим газохроматографическим анализом с галогенселективным электронозахватным детектором. Диапазон определяемых концентраций фенола в воде от 0.2 до 10 мкг/дм3 с относительной погрешностью не более 30 %. Объем пробы воды, необходимый для анализа, – 25 см3, продолжительность анализа – 30 минут.Ключевые слова: фенол, газовая хроматография, высокоцветные природные воды, химическая модификация, гумусовые вещества, оксид алюминияDOI: http://dx.doi.org/10.15826/analitika.2019.23.2.00

High-precision calculations of In I and Sn II atomic properties

We use all-order relativistic many-body perturbation theory to study 5s^2 nl configurations of In I and Sn II. Energies, E1-amplitudes, and hyperfine constants are calculated using all-order method, which accounts for single and double excitations of the Dirac-Fock wave functions.Comment: 10 pages, accepted to PRA; v2: Introduction changed, references adde

Donor DBH excitons and magnetism of Mn doped ZnO

In this paper the results of the study of optical absorption, photo-EPR signals and magnetic measurements of hydrothermal single crystals of zinc oxide doped with manganese were presented. Several lines were detected in optical absorption spectra at the temperature of 4.2 K and 77.3 K for σ- and π- polarizations of light in a 1.72-2.3 eV spectral range. These lines are attributed to a donor exciton [(d5 + h)e] that emerges as a result of the Coulomb binding of a free s electron and a hole, which is localized on p-d hybridized states. Properties of these lines are significantly different from the properties of lines of donor and acceptor excitons in II-VI:3d compounds. In EPR-spectra of Zn1-xMnxO crystals the intensity of allowed and forbidden EPR-signals of Mn2+ (d 5)-ions does not change under the illumination while the intensity of EPR-signals of unintentional Fe3+ (d 5)-ions decreases by 70 %. The value of the magnetic susceptibility of Zn1-xMnxO (x = 0.0009) is in linear dependence with temperature, which agrees with the Curie equation. Temperature dependence of the inverse value of the Mn2+ magnetic susceptibility indicates that the exchange interaction in ZnO:Mn crystals is absent. New experimental results allow us to assume that investigated Zn1-xMnxO (x = 0.0009) samples are semiconductors in the forbidden gap of which the donor level of d5/d4 does not exist. The hybridization of d5 states of Mn2+ and p states of the nearest four oxygen ions O2- leads to pushing out the antibonding DBH-states (d 5 + p) into the forbidden gap. The transitions of electrons from DBH-states to the conduction band provide a broad band of the impurity absorption in ZnO:Mn. Below this band we observed a, b, c and d lines, which are called dbh-donor excitons [(d5+h)e]. © Published under licence by IOP Publishing Ltd.Russian Academy of Medical Sciences, RAMS: 18-10-2-6.Ministry of Education and Science of the Russian Federation, MinobrnaukaThe research was carried out within the state assignment of Minobrnauki of Russia (theme “Magnet” No.АААА-А18-118020290129-5, theme “Electron” No. АААА-А18-118020190098-5) and within the state assignment no. 3.6115.2017/8.9 of the Ministry of Education and Science of the Russian Federation for the Ural Federal University, with the support of the grant of Ural branch of Russian Academy of Science № 18-10-2-6

Excitons and Photoluminescence in ZnO and Zn0.99Mn 0.01O Nanocrystals

The photoluminescence and photoluminescence excitation spectra for Zn 1-x Mn x O nanocrystals are presented. After annealing of powders in air, the intensity of the bands attributable to manganese decreases noticeably. This suggests that the oxygen vacancies affect the Zhang-Rice-like states appearing due to strong d-p-hybridization, which is confirmed by an increase in the band gap of Zn1-x Mn x O for low x. The origin of the 2.9-eV peak and the shape of its excitation spectrum are discussed qualitatively. For Zn1-x Mn x O nanocrystals, the shape of the excitation spectrum is as unusual as the intense absorption in the range (2.2-3.0) eV. © 2010 Pleiades Publishing, Ltd.We wish to thank T. Dietl, V.I. Anisimov, and A.V. Lukoyanov for the discussion of localized states in the Zn1–xMnxO system. This work was supported by the Russian Foundation for Basic Research (project nos. 07 02 00910_a and 08 02 99080r ofi), and Russian Federal Agency on Science and Innovations (grant no. 02.740.11.0217)

Optical Properties of Oxide Magnetic ZnO, Zn0.95Mn0.05O and Cu2O Nanopowders

ZnO, Zn0.95Mn0.05O and Cu2O nanocrystals are synthesized. Excitonic lines in absorption spectra of these materials are detected. In photoluminescence and photoluminescence excitation spectra of Zn0.95Mn0.05O the dangling bond hybrid (DBH) state is found. It has splitted out from the top of the valence band due to the hybridization between d-states of the Mn impurity and the p-states of oxygen. © 2009 Elsevier B.V. All rights reserved.The work was performed with the partial support of the Russian Foundation for Basic Research (Grants nos. 07-02-00910_a and 08-02-99080 r- ofi)