Quantitative analysis of the benzanthrone aminoderivative binding to amyloid fibrils of lysozyme

The accumulation of amyloid fibrils in different tissues is associated with a number of neurodegenerative diseases. Despite a huge variety of amyloid-specific probes, all of them suffer from many drawbacks, highlighting the necessity of searching for more preferable dyes. In the present work, the potential of new fluorescent probe AM3 for selective detection of fibrillar protein aggregates, formed from lysozyme, has been evaluated. To quantify the affinity of this dye for amyloid fibrils, the isotherms of dye binding to the fibrillar lysozyme have been derived from fluorimetric titration. Parameters of the dye-protein complexation: association constant, molar fluorescence and binding stoichiometry, calculated from the Langmuir adsorption model, revealed that AM3 interacts strongly with protein insoluble aggregates. High values of the binding parameters make AM3 an alternative to a widely-used amyloid-specific probe Thioflavin T. We also investigated the effects of polarity and viscosity on AM3 fluorescence properties. The binding of AM3 to the protein hydrophobic cavities has been followed by red shift of the dye emission spectra, which can be explained by H-bonding between proton-donating groups of the protein and carbonyl moiety of the probe. Long-wavelength shift of emission maximum was observed also upon increasing the excitation wavelength. This finding suggests that reorientation time of solvent molecules is higher, than the dye fluorescence lifetime. Fluorescence anisotropy studies revealed slow rotation diffusion of the probe, bound to amyloid fibrils being indicative of high viscosity of AM3 microenvironment. The observed photophysical properties of the new aminobenzanthrone derivative make AM3 a perspective probe for basic research and medical diagnostics

Interaction of novel benzanthrone derivative with amyloid lysozyme

A novel benzanthrone derivative AM18 was investigated with respect to its photophysical properties when bound to native, oligomeric and fibrillar hen egg white lysozyme. As shown by fluorimetric titration AM18 is more sensitive to pathogenic protein aggregates than Thioflavin T, however has no ability to differentiate between mature and immature lysozyme fibrils. The recovered affinity and fluorescence response of the novel probe to amyloid protein appeared to be similar to those of recently developed amyloid lysozyme-sensitive dyes like e. g. Nile Red and cyanine dye 7515. Despite the high increase of the probe emission in the presence of amyloid lysozyme compared to its fluorescence in buffer, the minimal amount that could be detected by 1 μM AM18 was 10 times lower for amyloid-native protein solutions due to high affinity of the dye for lysozyme monomers. In general, because of high quantum yields and “signal-to-noise” ratios in the presence of pathogenic protein aggregates AM18 appeared to be an effective tool for amyloid detection and characterization in vitro, being however unable to detect pathogenic protein aggregates in vivo like e.g. recently reported p-FTAA because of the sensitivity to lipids. Compared to previously reported AM3 a novel dye showed 2-fold lower “signal-to- noise” ratio in the presence of fibrillar lysozyme, and 2 fold lower blue shift of emission maximum. This tendency was explained in terms of decreased charge transfer from the donor to acceptor groupes of AM18 compared to AM3. Finally, as concluded from the comparison of AM18 and previously studied benzanthrone derivatives, the 5 nm – red edge excitation shift of AM18 is indicative of its possible binding to fibril “deep cavities”, containing no water. High anisotropy values of amyloid-bound dye led us to conclusion that the enhanced fluorescence of the probe is associated with the decrease of the rotational motion of the amino-substitute about the benzanthrone unit. This is a sign of AM18 behaviour as a molecular rotor

ОСОБЕННОСТИ ПОВЕДЕНИЯ СУЛЬФАТА НАТРИЯ В СИЛИКАТНЫХ РАСПЛАВАХ

Knowledge on sodium sulfate behavior in the silicate melts at the different synthesis conditions as a promising component of the batch for the production of hollow glass microspheres was extended.Приведены результаты исследования поведения сульфата натрия в силикатных расплавах при различных усло­виях синтеза как перспективного компонента шихты для получения полых стеклянных микросфер

Analysis against allergy on theterritory of Kachkanar town district

The article presents real state of pharma market medicine against allergyon the territory of Kachkanar town district. The indicator of the completeness of the product range was defined and formed 0, 45, that is insufficient. Investigatedpharmacy chain has only 40% from available number of pharmacy medicine of different packing and dosage against allergy. They studied difference of providing medical care for people in relation toarea of residence.В статье представлено актуальное состояние фармацевтического рынка лекарственных препаратов от аллергии на территории Качканарского городского округа. Был определен показатель полноты ассортимента по торговым названиям, который в среднем составил 0,45, что является недостаточным. На фармацевтическом рынке в исследуемой аптечной сети имеется лишь 40% от возможного количества лекарственных форм различных фасовок и дозировокпрепаратов от аллергии.Были изучены различия в оказании лечебной помощи людям в зависимости от района проживания города

ОПРЕДЕЛЕНИЕ КОФЕИНА В НАПИТКАХ МЕТОДОМ ВОЛЬТАМПМЕРОМЕТРИИ НА УГЛЕРОДСОДЕРЖАЩИХ ЭЛЕКТРОДАХ, МОДИФИЦИРОВАННЫХ АРИЛДИАЗОНИЕВЫМИ СОЛЯМИ

The method of carbon containing electrode (CCE) modification with tosylated arendiazonium salts (ADT) was proposed for the voltammetric (VA) determination of caffeine in beverages. The comparison of chemical spontaneous and electrochemical modification approaches was carried out for ADT modified CCE for VA caffeine determination for the first time. A new class of ADT is characterized by high solubility and stability for one month that plays significant role in the process of electrode surface modification. Salts with nitro and carboxy substituents were tested. The optimal conditions for the spontaneous chemical modification of the CCE were selected: ADT modifier with NO2 substituent, electrode immersion time in the modifier solution for 10 seconds, modifier concentration of 5 mg / dm3. ADT deposition on the electrode surface was confirmed by the IR spectroscopy and scanning electron microscopy with the formation of covalent bonds between the carbon atoms of electrode surface and the benzene rings of the modifier. It was shown that the electroactive surface area increases by two times after the modification. Consequently, the technique sensitivity increasing the detection limit of 51 mg / dm3 and linear range extension from 154 up to 500 mg / dm3 was observed. While applying the modified electrode, the analysis time was reduced to 15 minutes. Furthermore, the suitability of CCE modified with NO2 substituent was tested for the analytical purposes. As a result, the caffeine was determined in some tonic and carbonated drinks. The comparison of the results obtained by the proposed method with ADT modified CCE and the level declared by the manufacturer was carried out. The high compliance was established. In addition, the obtained data was consistent with the results by the independent spectrophotometric method.Keywords: caffeine, diazonium aromatic salts, modifier, carbon-containing electrode, voltammetry, spontaneous modification, SEM, IR spectroscopy, cyclic voltammetry  DOI: http://dx.doi.org/10.15826/analitika.2020.24.1.007E.V. Dorozhko, A.O. Gusar, E.A. Bedareva, G.B. Slepchenko, M.E. Trusova, E.I. Korotkova National Research Tomsk Polytechnic University,Lenina prosp., 30, Tomsk, 634050, Russian FederationПредложен способ модификации углеродсодержащих электродов (УСЭ) тозилатными солями арендиазония (АДТ) с нитро- и карбоксизаместителями для вольтамперометрического (ВА) определения кофеина в напитках. Впервые проведено сравнение спонтанного химического и электрохимического способов модификации УСЭ АДТ для ВА определения кофеина. Новый класс АДТ обладает хорошей растворимостью, стабильностью в течение одного месяца, что играет немаловажную роль в процессе модификации поверхностей электродов. Подобраны оптимальные условия спонтанной химической модификации УСЭ: модификатор АДТ с NO2-заместителем, время погружения электрода в раствор модификатора − 10 с, концентрация модификатора − 5 мг/дм3. Методами инфракрасной спектроскопии (ИК-спектроскопии) и сканирующей электронной микроскопии (СЭМ) подтверждено закрепление АДТ на поверхности УСЭ с образованием ковалентных связей между атомами углерода электродной поверхности и бензольными кольцами модификатора. Показано, что после модификации площадь электроактивной поверхности увеличивается в два раза. В результате этого наблюдается возрастание чувствительности определения кофеина с пределом обнаружения 51 мг/дм3 и расширение диапазона определяемых концентраций: 154-500 мг/дм3. При использовании модифицированного электрода время анализа сократилось до 15 минут. Кроме этого, наблюдалась стабильность поверхности электрода без обновления в течение недели. При апробации пригодности для аналитических целей УСЭ, модифицированного АДТ с NO2-заместителем, проведено определение кофеина в некоторых тонизирующих и газированных напитках. Полученные значения содержания кофеина в напитках разработанным методом с использованием УСЭ, модифицированного спонтанным химическим способом АДТ с NO2-заместителем, наглядно демонстрируют соответствие значениям, заявленным производителем, а также согласуются с результатами независимого спектрофотометрического метода. Ключевые слова: кофеин, ароматические соли диазония, модификатор, углеродсодержащий электрод, вольтамперометрия, спонтанная модификация, СЭМ, ИК-спектроскопия, циклическая вольтамперометрияDOI: http://dx.doi.org/10.15826/analitika.2020.24.1.00

Получение и исследование фотокаталитических свойств CeO2-TiO2 композитов для очистки воды от органических загрязнителей

Photocatalytically active CeO2-TiO2 composites have been prepared by the sol-gel method from inorganic precursors with varied СеО2/ТiO2 ratio. Their catalytic activity has been shown to be higher than that for individual СеО2 or TiO2 oxides and can be used for photocatalytic water purification.Фотокаталитически активные нанокомпозиты CeO2-TiO2 изготовлены золь-гель методом из неорганических прекурсоров с различным соотношением СеО2/TiO2. Обладают более высокой каталитической эффективностью, чем индивидуальные оксиды СеО2 или TiO2 и могут быть использованы для фотокаталитической очистки воды. Наиболее каталитически активны композиты с низким содержанием CeO2

Beyond graphene oxide: Laser engineering functionalized graphene for flexible electronics

Carbon nanomaterials, especially graphene, are promising due to their abundance and the possibility to exploit them in lightweight, flexible, and wearable electronics enabling paradigms such as the Internet of Things. However, conventional methods to synthesize and integrate graphene into functional materials and flexible devices are either hazardous, time demanding, or excessively energy-consuming. To overcome these issues, here we propose a new concept based on the laser processing of single-layer diazonium-functionalized graphene. This is a safe, inexpensive, and environmentally-friendly method making it a competitive alternative for graphene-device fabrication. Flexible chemiresistors exhibit sensitivity for breath (water vapor and CO2) and ethanol detection up to 1500% higher than laser-reduced graphene oxide devices. We attribute this enhanced sensitivity to an optimal balance between structural defects and electrical conductivity. Flexible electronic circuits demonstrate a superb resilience against scratching and high current stability up to 98% with durability against 180° bending cycles for continuous operation of several weeks. This work can impact biomedical technology and electronics where tunable electrical conductivity, sensitivity, and mechanical stability are of uttermost importance. © 2020 The Royal Society of Chemistry

Thermal expansion of KYbXY1-X(WO4)2 crystals

Average and differential linear thermal expansion coefficients of KYbxY1-x(WO4)2 crystals are determined in the directions of the optical indicatrix axes Np, Nm and Ng using dilatometric technique. Dependence of the average and differential linear thermal expansion coefficients on the temperature in the range of 75–290 C and ytterbium contains x from 0 to 1.0 are discussed

МЕТОДИКА ОЦЕНКИ РИСКА ПРЕДСТОЯЩЕГО ПОЛЕТА ДЛЯ ВЕРТОЛЕТОВ С УЧЕТОМ НЕБЛАГОПРИЯТНЫХ МЕТЕОУСЛОВИЙ

The task to provide flight safety is solved both at the stage of design and manufacture of aircraft and during its operation. Flight safety is influenced by three groups of factors: a human factor, a technical factor and marginal ambient conditions. In spite of the fact that only about 3% of aviation accidents are caused by marginal ambient conditions, in many cases there was a combination of the human factor as the main one with the availability of the accompanying unfavorable external conditions, especially marginal weather conditions. The article provides a comparative analysis of a flight safety factor in commercial civil aviation in the Russian Federation and the United States and analyzes accident statistics caused by adverse meteorological conditions. Since the greatest number of accidents related to marginal weather conditions occurred with helicopters, the article has highlighted the possibility of increasing helicopter flight safety by creating a methodology for risk assessment associated with the influence of adverse weather conditions before the flight operation. Risk assessment techniques, such as the ICAO Risk Assessment Matrix, the CFIT checklist, FRAT, have been analyzed and the feasibility of using the FRAT methodology has been demonstrated. On the basis of the FRAT methodology after updating the section "Operating conditions of the aircraft", a risk assessment methodology for the forthcoming flight of helicopters was obtained. A risk level admissibility scale for the forthcoming flight was proposed to interpret the obtained values of the risk level.Задача обеспечения безопасности полетов решается как на стадии проектирования и изготовления авиационной техники, так и при ее эксплуатации. На безопасность полетов влияют три группы факторов: человеческий фактор, технический фактор и неблагоприятные внешние условия. Несмотря на то, что только около 3 % авиационных происшествий обусловлены влиянием неблагоприятных внешних условий, во многих случаях имело место сочетание человеческого фактора как основного при наличии сопутствующих неблагоприятных внешних условий, в первую очередь неблагоприятных метеоусловий. В статье приведен сравнительный анализ уровня безопасности полетов в коммерческой гражданской авиации РФ и США, выполнен анализ статистики авиационных происшествий, связанных с влиянием метеоусловий. Так как наибольшее количество авиационных происшествий, связанных с влиянием неблагоприятных метеоусловий, произошло с вертолетами, в работе рассмотрена возможность повышения безопасности полетов вертолетов путем создания методики оценки рисков, связанных с влиянием неблагоприятных метеоусловий, перед выполнением конкретных полетов. Проанализированы методики оценки риска, такие как матрица оценки рисков ИКАО, контрольный перечень CFIT, FRAT, и показана целесообразность использования методики FRAT. На основе методики FRAT, после доработки раздела «Условия эксплуатации ВС», была получена методика оценки рисков на предстоящий полет для вертолетов. Для интерпретации полученных значений уровня риска была предложена шкала допустимости уровня риска для предстоящего полета