170 research outputs found
The list of species registered in taiga meadow community during succession under enhanced radioactive background
No full textThe data presented in this article are related to the research article entitled “The succession of the plant community on a decontaminated radioactive meadow site” (T. Maystrenko, B. Gruzdev, E. Belykh, A. Rybak, 2018) [1]. Primary data on floristic studies of meadow community development in taiga zone on the site contaminated with naturally occurring radionuclides are shown. The information given allows to follow a process of appearance and exclusion of high plant species from the pioneer step of succession up to stable community formation and to compare the structure and composition of meadow communities formed on territories with the enhanced and natural radioactivity background. Keywords: Restoration of vegetation cover, Meadow community development, Taiga zone, Radioactive contaminatio
Ultrastructural analysis of chromatin in meiosis I plus II of rye (Secale cereale L.)
No full textScanning electron microscopy (SEM) proves to be an appropriate technique for imaging chromatin organization in meiosis I and II of rye (Secale cereale) down to a resolution of a few nanometers. It could be shown for the first time that organization of basic structural elements (coiled and parallel fibers, chromomeres) changes dramatically during the progression to metaphase I and II. Controlled loosening with proteinase K (after fixation with glutaraldehyde) provides an enhanced insight into chromosome architecture even of highly condensed stages of meiosis. By selective staining with platinum blue, DNA content and distribution can be visualized within compact chromosomes as well as in a complex arrangement of fibers. Chromatin interconnecting threads, which are typically observed in prophase I between homologous and non-homologous chromosomes, stain clearly for DNA. In zygotene transversion of chromatid strands to their homologous counterparts becomes evident. In pachytene segments of synapsed and non-synapsed homologs alternate. At synapsed regions pairing is so intimate that homologous chromosomes form one filament of structural entity. Chiasmata are characterized by chromatid strands which traverse from one homolog to its counterpart. Bivalents are characteristically fused at their telomeric regions. In metaphase I and II there is no structural evidence for primary and secondary constrictions. Copyright (C) 2003 S. Karger AG, Basel
ОПРЕДЕЛЕНИЕ МОНОЗАМЕЩЕННЫХ НИТРОФЕНОЛОВ В ВОДЕ МЕТОДОМ ГАЗОВОЙ ХРОМАТОГРАФИИ
No full textNitrophenols 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
Fundamental mechanisms of nanosecond-laser-ablation enhancement by an axial magnetic field
No full textA steady magnetic field perpendicular to a laser beam is widely used to improve the rate and quality of laser ablation. Recently, we reported a 69-fold enhancement of laser ablation of silicon using a magnetic field parallel to a laser beam. To understand the fundamental mechanisms of that phenomenon, multipulse magnetic-field-enhanced ablation of stainless steel, titanium alloy, and silicon was performed. The influence of magnetic field varies significantly depending on the material: from 2.8-fold ablation enhancement on stainless steel and silicon to no pronounced ablation modification on titanium alloy. Those results are discussed in terms of magnetized-plasma, magneto-absorption, skin-layer, and magnetic-field-influenced transport effects. Understanding of those mechanisms is crucial for advanced control of nanosecond laser–surface coupling to improve laser micromachining.Agency for Science, Technology and Research (A*STAR)Accepted versionThe authors acknowledge A*StarSINGA scholarship and SIMTech for their support. Dr.Wolfgang Rudolph of the University of New Mexico is ac-knowledged for a kind suggestion to consider the skin-layereffects
Investigation of laser-induced ablation of ceramic materials for spaceborne applications
No full textIn this work tests for determination of ablation thresholds of various ceramic materials for pulsed laser irradiations at
wavelengths of 355 nm and 1064 nm in vacuum are presented. For comparison tests with copper and aluminium are also reported. The ablation process was monitored insitu by long-distance microscopy. The morphology of ablation spots was exsitu inspected by scanning electron microscopy. Furthermore, the redeposition of potentially released particles on
optics in the vicinity to the target was examined
Chaos and Harmony in Nature and Art as the Origin of Beauty
No full textThe relevance of the topic “beauty” is inexhaustible. In this article, it is considered as the unity of two opposites—chaos and harmony. This unity is the basis on which art is built, as an activity inextricably linked with beauty. The study subject was these two concepts, and the study object is the entire aesthetic thought from ancient times, considering beauty as a combination of chaos and harmony. The study purpose was to show how this idea of the unity of two opposites, embedded in the structure of the universe, is the main driving force of any creative activity. Human culture is considered at the same time as a process aimed at harmonizing chaos, and art as an opportunity to give this process expressive forms. In the study, along with the philosophical and aesthetic methodology, methods of other sciences such as hermeneutical, axiological, existential-phenomenological, semiotic, and psychological were applied. When writing the study, there were used a wide range of sources: works of ancient thinkers Hesiod, the pre-Socratics, Plato, Pythagoras, Aristotle, Russian aesthetic and psychological thought of A.F. Losev, V.S. Solovyov, N.A. Berdyaev, Yu.N. Lotman, Yu.B. Borev, L.S. Vygotsky, works of Russian and foreign scientists, including A.V. Voloshinov, Yu.V. Taboyakova, B. Mandelbrot, H.-O. Paytgen, P.H. Richter, N.T. Rymar, G.P. Menchikov, studies in ornament art of V.V. Ivanov, V.N. Toporov, V. Gruzdev, K. Buher, and T.V. Kolchev. The author concludes that the unity of chaos and harmony is represented in art as a natural reality in which opportunity and action are combined. In this strange dyad is the basis of what we call creativity. And all this is contained in the universe, as a certain formula by which the beauty of the world and the beauty of art are built
The list of species registered in taiga meadow community during succession under enhanced radioactive background
No full textDerivatization in gas chromatographic determination of phenol and aniline traces in aqueous media
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