ОПРЕДЕЛЕНИЕ ФЕНОЛЬНЫХ СОЕДИНЕНИЙ В ДЕЗИНФЕКЦИОННЫХ СРЕДСТВАХ

The aspects of analytical determination of disinfectants derivatives of the phenol series аrе considered. The possibility of codetermination of five derivatives of this series in different disinfectants using the RP-HPLC method in the isocratic mode (UV detection) is shown. Alternatively, the possibilities of the determination with the use of spectrophotometry and GC methods are considered. This study and previous ones showed that the extraction of phenol derivatives by organic solvents from а wide range of disinfectants is feasible only in some cases, preferably with the use of hexane as an extractant. Further spectrophotometry of hexane extracts does not always enable to correctly compensate for the effect of background impurities and requires an additional separation of the components. The literature data and experimental results suggest that it is more efficient to analyze the whole series of disinfectants in isopropanol (sometimes in water) by chromatographic methods, preferably by HPLC. Sample preparation reduces to the solubilization of batches of ready-made disinfectants in isopropanol/water. It is optimal to carry out the chromatographic study using elution with acetonitrile-based systems (for example, СН3СN:Н2O, 60:40) providing the correct determination (λ = 280 nт) of phenol derivatives. The completeness of extraction (if the extraction method is used), as well as the metrology aspects of all the analytical determination is set directly in а laboratory during the realization of procedures of introduction/validation according to the internal documents of the system quality management for the relevant structural unit.Рассмотрены аспекты аналитического определения дезинфектантов производных ряда фенола. Показана возможность совместного определения пяти производных данного ряда в различных дезинфицирующих средствах с использованием ОФ ВЭЖХ в изократическом режиме (УФ-детектирование). Альтернативно рассмотрены возможности определения с использованием методов спектрофотометрии и ГЖХ. Настоящее и предшествующие исследования показали, что экстракционное извлечение производных группы фенола органическими растворителями из широкого спектра дезинфицирующих средств доступно только в некоторых случаях, преимущественно при использованием гексана в качестве экстрагента. В дальнейшем спектрофотометрирование гексановых экстрактов не всегда позволяет корректно скомпенсировать влияние фоновых примесей и требует дополнительного разделения компонентов. Исходя из литературных данных и результатов экспериментов, стоит отметить, что производительнее осуществлять анализ всей линейки дезинфекционных препаратов в изопропаноле (иногда в воде) хроматографическими методами, отдавая предпочтение ВЭЖХ. При этом пробоподготовка сводится к солюбилизации навесок готовых средств в изопропаноле/воде. Хроматографическое исследование оптимально проводить с применением в качестве элюента систем на основе ацетонитрила, обеспечивающих корректное определение (λ = 280 нм) производных фенола

Macro- And microstructural changes in cosmonauts' brains after long-duration spaceflight

Long-duration spaceflight causes widespread physiological changes, although its effect on brain structure remains poorly understood. In this work, we acquired diffusion magnetic resonance imaging to investigate alterations of white matter (WM), gray matter (GM), and cerebrospinal fluid (CSF) compositions in each voxel, before, shortly after, and 7 months after long-duration spaceflight. We found increased WM in the cerebellum after spaceflight, providing the first clear evidence of sensorimotor neuroplasticity. At the region of interest level, this increase persisted 7 months after return to Earth. We also observe a widespread redistribution of CSF, with concomitant changes in the voxel fractions of adjacent GM. We show that these GM changes are the result of morphological changes rather than net tissue loss, which remained unclear from previous studies. Our study provides evidence of spaceflight-induced neuroplasticity to adapt motor strategies in space and evidence of fluid shift- induced mechanical changes in the brain. © 2020The Authors, some rights reserved.Peer reviewe

The effect of prolonged spaceflight on cerebrospinal fluid and perivascular spaces of astronauts and cosmonauts

peer reviewedLong-duration spaceflight induces changes to the brain and cerebrospinal fluid compartments and visual acuity problems known as spaceflight-associated neuro-ocular syndrome (SANS). The clinical relevance of these changes and whether they equally affect crews of different space agencies remain unknown. We used MRI to analyze the alterations occurring in the perivascular spaces (PVS) in NASA and European Space Agency astronauts and Roscosmos cosmonauts after a 6-mo spaceflight on the International Space Station (ISS). We found increased volume of basal ganglia PVS and white matter PVS (WM-PVS) after spaceflight, which was more prominent in the NASA crew than the Roscosmos crew. Moreover, both crews demonstrated a similar degree of lateral ventricle enlargement and decreased subarachnoid space at the vertex, which was correlated with WM-PVS enlargement. As all crews experienced the same environment aboard the ISS, the differences in WM-PVS enlargement may have been due to, among other factors, differences in the use of countermeasures and high-resistive exercise regimes, which can influence brain fluid redistribution. Moreover, NASA astronauts who developed SANS had greater pre- and postflight WM-PVS volumes than those unaffected. These results provide evidence for a potential link between WM-PVS fluid and SANS. Copyright © 2022 the Author(s). Published by PNAS. This open access article is distributed under Creative Commons Attribution License 4.0 (CC BY)

THE DETERMINATION OF PHENOLS COMPOUNDS IN DISINFECTANTS

The aspects of analytical determination of disinfectants derivatives of the phenol series аrе considered. The possibility of codetermination of five derivatives of this series in different disinfectants using the RP-HPLC method in the isocratic mode (UV detection) is shown. Alternatively, the possibilities of the determination with the use of spectrophotometry and GC methods are considered. This study and previous ones showed that the extraction of phenol derivatives by organic solvents from а wide range of disinfectants is feasible only in some cases, preferably with the use of hexane as an extractant. Further spectrophotometry of hexane extracts does not always enable to correctly compensate for the effect of background impurities and requires an additional separation of the components. The literature data and experimental results suggest that it is more efficient to analyze the whole series of disinfectants in isopropanol (sometimes in water) by chromatographic methods, preferably by HPLC. Sample preparation reduces to the solubilization of batches of ready-made disinfectants in isopropanol/water. It is optimal to carry out the chromatographic study using elution with acetonitrile-based systems (for example, СН3СN:Н2O, 60:40) providing the correct determination (λ = 280 nт) of phenol derivatives. The completeness of extraction (if the extraction method is used), as well as the metrology aspects of all the analytical determination is set directly in а laboratory during the realization of procedures of introduction/validation according to the internal documents of the system quality management for the relevant structural unit

The determination of polymeric derivatives of guanidine in disinfectants by two-phase titration

The article considers the results of identifying the disinfectant water-soluble guanidines polymers by means of methods including spectrophotometry, infrared spectroscopy, fluorescence analysis, as well as the use of gold nanoparticles. The present work describes the results of polyhexamethyleneguanidine (PHMG) identification in finished compositions. It is shown that auxiliary components such as quaternary ammonium compounds prevent the identification of the PHMG in the mixture. So, most known methods are ineffective or require additional manipulations. The method of quantitative analysis of polyhexamethyleneguanidine (PHMG) and polyhexamethylenebiguanidine (PHMB) in disinfectants by means of two-phase titration with sodium dodecyl sulfate in the presence of bromophenol blue indicator was proposed. The end point was detected visually. This method allows taking into account the additive contributions of quaternary ammonium compounds in PHMG titration results. In this case, the titration at all stages of the determination of PHMG is conducted with sodium dodecy sulfate solutions with the same concentrations and the same weighed portions of sample are taking. Other disinfectants, namely hydrogen peroxide, alcohols, primary, secondary, tertiary amines, including N,N-bis(3-aminopropyl)dodecylamine present in the solution do not interfere with the identification of PHMG

Alcoxotechnology for obtaining heat-resistant materials based on rhenium and ruthenium

Objectives. To develop physical and chemical bases and methods to obtain rhenium–ruthenium isoproxide Re4-yRuyO6(OPri)10 —a precursor for obtaining a high-temperature alloy—from ruthenium acetylacetonate and rhenium isoproxide acquired by electrochemical methods.Methods. IR spectroscopy (EQUINOX 55 Bruker, Germany), X-ray phase and elemental analyses, energy-dispersive microanalysis (EDMA, SEM JSM5910-LV, analytical system AZTEC), powder X-ray diffraction (diffractometer D8 Advance Bruker, Germany), experimental station XSA beamline at the Kurchatov Synchrotron Radiation Source.Results. The isoproxide complex of rhenium–ruthenium Re4-yRuyO6(OPri)10 was obtained, and its composition and structure were established. Previously conducted quantum chemical calculations on the possibility of replacing rhenium atoms with ruthenium atoms in the isopropylate complex were experimentally proven, and the influence of the electroconductive additive on the composition of the obtained alloy was revealed.Conclusions. Physical and chemical bases and methods for obtaining rhenium–ruthenium isoproxide Re4-yRuyO6(OPri)10 were developed. The possibility of using rhenium–ruthenium Re4-yRuyO6(OPri)10 as a precursor in the production of ultra- and nanodisperse rhenium–ruthenium alloy powders at a record low temperature of 650°C were shown

Алкоксотехнология получения жаропрочных материалов на основе рения и рутения

Objectives. To develop physical and chemical bases and methods to obtain rhenium–ruthenium isoproxide Re4-yRuyO6(OPri)10 —a precursor for obtaining a high-temperature alloy—from ruthenium acetylacetonate and rhenium isoproxide acquired by electrochemical methods.Methods. IR spectroscopy (EQUINOX 55 Bruker, Germany), X-ray phase and elemental analyses, energy-dispersive microanalysis (EDMA, SEM JSM5910-LV, analytical system AZTEC), powder X-ray diffraction (diffractometer D8 Advance Bruker, Germany), experimental station XSA beamline at the Kurchatov Synchrotron Radiation Source.Results. The isoproxide complex of rhenium–ruthenium Re4-yRuyO6(OPri)10 was obtained, and its composition and structure were established. Previously conducted quantum chemical calculations on the possibility of replacing rhenium atoms with ruthenium atoms in the isopropylate complex were experimentally proven, and the influence of the electroconductive additive on the composition of the obtained alloy was revealed.Conclusions. Physical and chemical bases and methods for obtaining rhenium–ruthenium isoproxide Re4-yRuyO6(OPri)10 were developed. The possibility of using rhenium–ruthenium Re4-yRuyO6(OPri)10 as a precursor in the production of ultra- and nanodisperse rhenium–ruthenium alloy powders at a record low temperature of 650°C were shown.Цели. Разработка физико-химических основ и способов получения изопроксида рения-рутения Re4-yRuyO6(OPri)10 из ацетилацетоната рутения и изопроксида рения, полученного электрохимическим методом – прекурсора получения высокотемпературного сплава.Методы. ИК-спектроскопия (EQUINOX 55 Bruker, Германия), рентгенофазовый и элементный анализ, энергодисперсионный микроанализ (ЭДМА, СЭМ JSM5910–LV, аналитическая система AZTEC), порошковая рентгеновская дифракция (дифрактометр D8 Advance Bruker, Германия), экспериментальная станция «РСА» Курчатовского источника синхротронного излучения.Результаты. Получен изопроксидный комплекс рения-рутения Re4-yRuyO6(OPri)10 , подтверждены его состав и строение. Экспериментально подтверждены ранее проведенные квантово-химические расчеты, свидетельствующие о возможности замещения атомов рения атомами рутения в изопропилатном комплексе. Выявлено влияние электропроводящей добавки на состав получаемого сплава.Выводы. Разработаны физико-химические основы и предложены способы получения изопроксида рения-рутения Re4-yRuyO6(OPri)10 , который может найти применение в качестве предшественника при получении ультра- и нанодисперсных порошков сплавов рений-рутений при рекордно низкой температуре 650 °C

Определение содержания полимерных производных гуанидина в антисептических средствах методом двухфазного титрования

The article considers the results of identifying the disinfectant water-soluble guanidines polymers by means of methods including spectrophotometry, infrared spectroscopy, fluorescence analysis, as well as the use of gold nanoparticles. The present work describes the results of polyhexamethyleneguanidine (PHMG) identification in finished compositions. It is shown that auxiliary components such as quaternary ammonium compounds prevent the identification of the PHMG in the mixture. So, most known methods are ineffective or require additional manipulations. The method of quantitative analysis of polyhexamethyleneguanidine (PHMG) and polyhexamethylenebiguanidine (PHMB) in disinfectants by means of two-phase titration with sodium dodecyl sulfate in the presence of bromophenol blue indicator was proposed. The end point was detected visually. This method allows taking into account the additive contributions of quaternary ammonium compounds in PHMG titration results. In this case, the titration at all stages of the determination of PHMG is conducted with sodium dodecy sulfate solutions with the same concentrations and the same weighed portions of sample are taking. Other disinfectants, namely hydrogen peroxide, alcohols, primary, secondary, tertiary amines, including N,N-bis(3-aminopropyl)dodecylamine present in the solution do not interfere with the identification of PHMG.Предложен титриметрический метод определения солей полигексаметиленгуанидина и полигексаметиленбигуанидина в антисептических средствах. Определение проводили методом двухфазного титрования в системе вода-хлороформ раствором додецилсульфата натрия в присутствии индикатора бромфенолового синего, окончание титрования устанавливали визуально. Предложенный метод не требует сложной подготовки, специального оборудования, отличается малым временем анализа (10-15 мин) и может быть рекомендован для проведения контроля качества антисептических средств

Brain Tissue-Volume Changes in Cosmonauts

[No abstract available

Alterations of functional brain connectivity after long-duration spaceflight as revealed by fMRI

The present study reports alterations of task-based functional brain connectivity in a group of 11 cosmonauts after a long-duration spaceflight, compared to a healthy control group not involved in the space program. To elicit the postural and locomotor sensorimotor mechanisms that are usually most significantly impaired when space travelers return to Earth, a plantar stimulation paradigm was used in a block design fMRI study. The motor control system activated by the plantar stimulation involved the pre-central and post-central gyri, SMA, SII/operculum, and, to a lesser degree, the insular cortex and cerebellum. While no post-flight alterations were observed in terms of activation, the network-based statistics approach revealed task-specific functional connectivity modifications within a broader set of regions involving the activation sites along with other parts of the sensorimotor neural network and the visual, proprioceptive, and vestibular systems. The most notable findings included a post-flight increase in the stimulation-specific connectivity of the right posterior supramarginal gyrus with the rest of the brain; a strengthening of connections between the left and right insulae; decreased connectivity of the vestibular nuclei, right inferior parietal cortex (BA40) and cerebellum with areas associated with motor, visual, vestibular, and proprioception functions; and decreased coupling of the cerebellum with the visual cortex and the right inferior parietal cortex. The severity of space motion sickness symptoms was found to correlate with a post-to pre-flight difference in connectivity between the right supramarginal gyrus and the left anterior insula. Due to the complex nature and rapid dynamics of adaptation to gravity alterations, the post-flight findings might be attributed to both the long-term microgravity exposure and to the readaptation to Earth's gravity that took place between the landing and post-flight MRI session. Nevertheless, the results have implications for the multisensory reweighting and gravitational motor system theories, generating hypotheses to be tested in future research