In this study, the one-pot synthesis of glycidol from glycerol (Gly) and dimethyl carbonate (DMC) was demon-strated in the presence of novel composite materials based on the microporous layered titanosilicate AM-4 (Aveiro-Manchester material number 4) and a zeolitic imidazolate framework ZIF-8. It was found that the re-action rate and selectivity towards glycidol depended on the ZIF-8 content in composite. Maximum 74.4% yield of glycidol with 92.5% conversion of glycerol was observed in the presence of 0.5%ZIF-8/AM-4 at DMC/Gly-molar ratio of 2, catalyst/glycerol weight ratio of 7.9 wt.% and temperature of 100 degrees C for 8 h. The catalytic properties of developed ZIF-8/AM-4 composite correlated with (1) ZIF-8 particle size, (2) the decreasing basic sites strength, and (3) the increasing microporosity of materials.

A series of Zn- and Co containing zeolitic-imidazolate frameworks (ZIFs), such as ZIF-8(Zn)/ZIF-67(Co), MAF-5(Zn)/MAF-5(Co), and MAF-6(Zn)/MAF-6(Co), were investigated as catalysts for the synthesis of propylene carbonate (PC) from propylene oxide (PO) and CO2. The effect of the chemical composition, textural, structural and physicochemical properties on their activity was investigated. It was found that the activity of Zn-containing materials was higher in comparison with Co-based materials. Moreover, the yield of a PC was decreased with increasing Co content in structure of mixed Zn,Co-ZIFs (ZIF-8/ZIF-67) that was related to the accessibility of active centers to reagents and the strength of their interaction with CO2 and propylene oxide. The catalytic performance of Zn-ZIFs was found to improve with increasing the size of pore aperture due to the guest molecule facile diffusion and accessibility of the active site for reagent. In general, based on the results of the present work, the Zn-ZIFs could be considered as promising catalysts for cycloaddition of CO2 to epoxides and thereby opens new paths for further research.

In August 2019, four descending (gravity) springs in the Inya River valley were sampled during the field works conducted within the study of low-radon waters of the Novosibirsk urban agglomeration in the area lying away from known granite massifs. Laboratory analyses have revealed enhanced radon activity concentrations (from 5 to 149 Bq/dm(3)). It has been established that these waters are fresh, of HCO3 Mg-Ca chemical composition, and have a TDS value of 413 to 548 mg/dm(3) and a silicon content of 4.1-8.6 mg/dm(3). They are characterized by neutral to slightly alkaline pH (7.1-8.4) and oxidizing geochemical conditions with Eh from +205.3 to +231.8 mV and O-2dissolv. = 6.24-12.26 mg/dm(3). The revealed predominance of SO42- over Cl- concentrations in the waters of the study area was probably due to the presence of sulfides in the water-bearing sediments, in particular, pyrite in the surface sediments. More than tenfold proportional excess of Ca concentrations over Si in the Inskie spring waters indicates the predominantly carbonate composition of the water-bearing sediments. The gross alpha-activity of waters is 3-4 mBq/dm(3), and gross beta-activity is 11-15 mBq/dm(3). Natural radionuclides are found in the spring waters within the following limits (mg/dm3): U-238, from 2.83 center dot 10(-3) to 4.13 center dot 1(0-)3; Th-232, from 2.39 center dot 10(-6) to 1.16 center dot 10(-5), and Ra-226, from 3.83 center dot 10(-10) to 4.93 center dot 10(-10). The value of the Th-232/U-238 ratio for the waters ranges from 5.79 center dot 10(-4) to 3.61 center dot 10(-3), as a result of the oxidative geochemical migration-arresting capability of thorium. The uranium isotope ratio (gamma) U-234/U-238 varies from 2.6 to 3.2 for the waters, with the uranium isotope activity determined as 117-124 mBq/dm(3) for U-234 and 38-48 mBq/dm(3) for U-238. This indicates shallow circulation of the studied waters as compared with those of the Svyatoi spring in Verkh-Tula Village, for which gamma = 1.3; the U-234 activity, 147 mBq/dm(3); and the U-238 activity, 115 mBq/dm(3). By isotopic composition, the origin of the spring waters is assigned to the infiltration type, and they are characterized by relatively narrow distribution of delta O-18 (from -17.5 to -16.7 parts per thousand) and delta D (from -128.4 to -126.2 parts per thousand) values. The delta(CDIC)-C-13 values are from -10.3 and -10.9 parts per thousand in springs 3 and 2 and become lighter (-11.2 and -12.1 parts per thousand) in springs 1 and 4, respectively. This is due to significant participation of surface waters in the recharge mechanism of springs 1 and 4, which is also consistent with the delta O-18 and delta D data and C-14 dating. The estimated age of water-dissolved carbon is 1478 +/- 81 years for the waters of spring 3 (the oldest), while it is found to be only 651 +/- 53 years for spring 4 and is estimated as modern for spring 1. The reported decline in the age of water-dissolved carbon down to recent age is indicative of increased contribution of surface water to the spring recharge area. The C and O isotope compositions of calcite of the host aquifer rocks are characterized by close values for most of the samples: delta(13). varies within narrow limits (from -3.1 to -2.7 parts per thousand), and delta O-18 varies from 17.2 to 18.4 parts per thousand. The isotopic composition becoming lighter for carbon (up to -11.0 parts per thousand) and oxygen (up to 13.9 parts per thousand) was noted for weathered schist samples. Results of the carbon isotope analysis of rock samples, their organic component, and water indicate an active isotopic exchange in the water-rock-organic matter system.

Актуальность исследования заключается в получении актуальных изотопно-геохимических данных о природных водах и вмещающих горных породах проявления радоновых вод Седова Заимка. Цель: изучить особенности химического состава природных вод и водовмещающих пород и получить первые сведения по активности 222Rn и изотопному составу δD, δ18O, δ13С, 234U, 238U, 226Ra и 228Ra. Методы. Лабораторное изучение химического состава методами титриметрии, ионной хроматографии, масс-спектрометрии с индуктивно связанной плазмой проводилось в ПНИЛ гидрогеохимии ИШПР ТПУ. Определение комплекса величин δD, δ18O, δ13СDIC вод и растворенного неорганического углерода (Dissolved Inorganic Carbon (DIC)) проводилось в центре коллективного пользования ИГМ СО РАН с помощью прибора Isotope Ratio Mass Spectrometer FinniganTM MAT 253, снабженного приставками пробоподготовки H/Device (для определений δD) и GasBench II (для определений δ18O и δ13СDIC). Измерение содержаний 222Rn в водах проводилось на комплексе «Альфарад плюс» в лаборатории гидрогеологии осадочных бассейнов Сибири ИНГГ СО РАН. Данные по общей β-активности вод, а также активностях 234U, 238U, 226Ra и 228Ra получены после предварительной радиохимической пробоподготовки на альфа-спектрометре ALPHA-ENSEMBLE-8 (Ametek, ORTEC, США); гамма-спектрометрической системе, скомпонованной на базе колодезного коаксиального HPGe ППД с низкофоновым криостатом EGPC 192-P21/SHF 00-30A-CLF-FA фирмы EURISYS MEASURES (Франция) и альфа-бета радиометре для измерения малых активностей УМФ-2000 с кремниевым детектором (НПО «Доза», Россия). Разделение данных на однородные геохимические совокупности выполнено с помощью коэффициентов Са/Na, Са/Mg, Ca/Si, Mg/Si, Na/Si. Для выявления степени концентрирования химических элементов в природных водах были рассчитаны коэффициенты концентрации  и водной миграции (по А.И. Перельману) . Результаты. Открыто проявление радоновых вод Седова Заимка, и впервые выполнены комплексные изотопно-геохимические исследования. Радоновые воды (активность 222Rn до 428 Бк/дм3) в основном характеризуются HCO3 Mg-Na-Ca составом с величиной общей минерализации от 158 до 581 мг/дм3 и содержанием кремния от 4,34 до 30,84 мг/дм3. Геохимические параметры среды варьируют от восстановительной до окислительной обстановки с величинами Eh от –40,2 до +28,4 мВ; pH от 7,5 до 7,6 и O2раств. от 2,99 до 5,24 мг/дм3. Значения геохимических коэффициентов составляют: Ca/Na 77,17; Ca/Mg 6,63; Ca/Si 11,42; Mg/Si 1,48; Na/Si 0,92; Si/Na 15,34; rNa/rCl 2,12; SO4/Cl 4,02, что закономерно указывает на процессы формирования химического состава радоновых вод во вмещающих породах преимущественно алюмосиликатного состава. Среди микрокомпонентов наиболее высокими средними содержаниями выделяются (мг/дм3): Si=17,77; Fe=1,18; Mn=0,16; Zn=0,020 и W=0,0036. Значимых коэффициентов концентрации микрокомпонентов не выявлено. Сильной миграционной способностью в растворе обладает Sr, средней – Si, Mn, Ba, Cs и U. Суммарная β-активность вод составляет 32 мБк/дм3. Содержания природных радионуклидов варьируют (мг/дм3): 238U от 3,91∙10–4 до 6,39∙10–4; 232Th от 6,02∙10–6 до 2,37∙10–5 и 226Ra от 6,66∙10–11 до 1,09∙10–10. 232Th/238U отношение в водах изменяется от 1,02∙10–2 до 3,71∙10–2, что является следствием окислительной геохимической обстановки, в которой торий не мигрирует. Уранизотопное отношение (γ) 234U/238U составляет 5,75 при активности изотопов урана (мБк/дм3): 234U (115±7), 238U (20±2), что указывает на неглубокую циркуляцию изученных вод. Активность изотопов радия в водах равна у 226Ra 70±7, а у 228Ra 51,8±3,9 мБк/дм3. Отношение 226Ra/228Ra в HCO3 Mg-Na-Ca радоновых водах составляет 1,35. Изотопный состав радоновых вод (от –126,3 до –121,1 ‰ для δD и от –16,8 до –16,3 ‰ для δ18O) указывает на их метеорно-инфильтрационное происхождение. Изотопный состав углерода δ13CDIC указывает на биогенное происхождение углекислоты и ее участие в процессе карбонат-силикатного выветривания пород.

Porous carbon (PC) materials with a large specific surface area and high volume of mesopores were produced using iron-doped calcium tartrate (CaTr) as a template precursor and ethanol as a carbon source. The iron doping concentration was varied from 0.2 to 1.6 at%. Template precursor was decomposed in argon at 800 degrees C, the formed template nanoparticles were immediately used for chemical vapor deposition (CVD) of ethanol, and after the synthesis, they were removed by HCl treatment. It was shown that the template consisted of CaO nano particles 5-20 nm in size with oxidized carbon layers on the surface. The incorporation of iron into CaTr promoted graphitization of the carbon layers and led to formation of iron oxide nanoparticles 3-4 nm in size. These nanoparticles served as a replica for small mesopores in the graphitic layers obtained in the ethanol CVD process. PC materials grown on the templates with an iron doping 0.2-0.4 at% were enriched with small mesopores, and due to this, they had a surface area of 907-931 m(2) g(-1) and pore volume of 3.3 cm(3) g(-1). These materials showed the highest specific capacitances of 280-230 F g(-1) at 2 mV s(-1) in 1 M H2SO4 electrolyte and a good rate capability.

The utilization of chlorine-containing organic wastes remains an actual problem. In the present research, sponge-like porous Ni-Mo-W alloys were prepared and used as catalysts for the catalytic chemical vapor deposition of 1,2-dichloroethane. The synthesis of the alloys was performed via a facile approach of high-temperature reductive thermolysis of the preliminarily prepared multicomponent precursors. The formation of alloys of exact composition was proven by precise X-ray diffraction analysis. The catalytic activity of the alloys in the decomposition of 1,2-dichloroethane was studied in a flow-through reactor at 600 degrees C for 2 h. The simultaneous presence of Mo and W in the composition of the Ni-based alloys was shown to have a synergetic effect on the process efficiency. The diameter of these fibers was found to be comparable with the size of metal particles formed as a result of initial alloys self-disintegration under the action of the aggressive reaction medium. (C) 2021 Elsevier B.V. All rights reserved.

TiO2 (rutile) samples with a hierarchical 3D nanostructure of the particles were synthesized by two methods: liquid hydrolysis of TiCl4 at 90 °С and atmospheric pressure; hydrothermal synthesis from TiCl4 at 160 °С and different [H2O]/[Ti] ratios. The effect exerted by conditions of the synthesis and post-treatments on the crystallite size, morphology, electronic properties and pore structure of the rutile samples was investigated. It was shown that severe hydrothermal conditions with the ratio [H2O]/[Ti] = 20 provide the formation of a more perfect crystal structure of rutile with a smaller band gap energy (3.00 eV against 3.06 eV for the rutile obtained by liquid hydrolysis at atmospheric pressure). The study revealed the stabilizing effect of cerium cations on the pore structure of rutile, which changes upon thermal treatment.

We offer a simple synthesis of porous nanostructured MoS2 materials by the rapid decomposition of ammonium tetrathiomolybdate aerogel in an inert atmosphere at temperatures of 400–700 °C. The synth...

The sulfonated (SO3H-functionalized) carbon nanomaterials were obtained by direct sulfonation of the initial carbon nanofibers and nanotubes. Concentrated sulfuric acid, oleum (20% SO3) and sulfonating mixtures containing 5 wt% MSO4 /H2SO4 (98%; M = VO2+, Cu2+, etc.) were used as a sulfating agents. It was shown that the use of MSO4/H(2)SO(4 )sulfonating mixtures allows achieving the efficiency of the sulfonation comparable with the case of oleum. Thus, in the case of the most effective sulfonating mixtures containing such ions as VO2+, Cu2+, Fe3+ , the values of the sulfur content were 1.2, 1.1 and 1.15 wt%, respectively. The optimal temperature of the sulfonation process was found to be in a range of 180-200 degrees C. All this provides a high acidity of the obtained materials along with maintaining the textural parameters (specific surface area of similar to 100 and similar to 300 m(2)/g for CNF and CNT, respectively). The structural changes of the materials taking place during the sulfonation process were studied by means of low-temperature nitrogen adsorption, X-ray photoelectron spectroscopy, Raman spectroscopy, high resolution transmission electron microscopy, and both the titrimetric and elemental analyses. According to the data obtained, high efficiency of the sulfonating mixtures is stipulated by the process of oxidative destruction of the surface layer of the carbon material that leads to an increase of its defectiveness thus enhancing the sulfonation efficiency.

N2 adsorption isotherms at ca. 77 K on macroporous α-Al2O3 have been measured and analyzed in the frameworks of the classic thermodynamic approach, with independent experimental data obtained by means of SEM-EDX, XRD, TGA, helium pycnometry, and mercury porosimetry taken into account. It is shown, that presence of adsorbed water considerably influences N2 adsorption, which gradually increases with temperature of the degas treatment. Simultaneously, the shape of the isotherms has a trend to change from Type II to Type VI, that assumes changing of adsorption mechanism from progressive increasing of the adsorbed layer thickness towards layer-by-layer adsorption. Corrected and smoothed isotherms are presented in the tabular form as reference for subsequent more comprehensive analysis using molecular statistical approaches.

By means of elemental and X-ray powder diffraction analysis, N2 adsorption at –196°C and CO2 adsorption at 0°C the textural properties of KNaLSX zeolite were studied after ion exchange modification in 1M NH4Cl solution followed by vacuum degassing at 40°C or drying in air at 120°C. The possibility of retaining the microporous structure of zeolite in the former case and its partial destruction in the latter case is shown.

By means of elemental and X-ray powder diffraction analysis, N 2 adsorption at –196°C and CO 2 adsorption at 0°C the textural properties of KNaLSX zeolite were studied after ion exchange modification in 1M NH 4 Cl solution followed by vacuum degassing at 40°C or drying in air at 120°C. The possibility of retaining the microporous structure of zeolite in the former case and its partial destruction in the latter case is shown.

The tert-butanol (TBA)-water system is studied in relation to increasing the efficiency of obtaining pharmaceutical powders by freeze-drying. Trehalose was used as a model target product. We report the X-ray diffraction and thermal analysis data which add surprising new information to the phase diagram of this previously repeatedly studied system. The freezing protocol has a strong impact on the specific surface area of the trehalose freeze-dried cakes and on the primary drying time. This is related to a discrepancy between the kinetic and thermodynamic stabilities of several TBA hydrates: di-hydrate (H1), heptahydrate (H2), and decahydrate (H3).

By means of elemental and X-ray powder diffraction analysis, N2 adsorption at –196°C and CO2 adsorption at 0°C the textural properties of KNaLSX zeolite were studied after ion exchange modification in 1M NH4Cl solution followed by vacuum degassing at 40°C or drying in air at 120°C. The possibility of retaining the microporous structure of zeolite in the former case and its partial destruction in the latter case is shown.

A method for the low-temperature synthesis of titania with the 3D rutile nanostructure was developed, and the effect of introduced cerium ions on the thermal stability of the material was studied. According to XRD, TEM, Raman spectroscopy and BET data, the introduction of 3 - 10 wt.% Ce into the rutile matrix decreases the growth of nanorutile crystallites under the action of high temperatures ranging from 300 1000 degrees C and provides the formation of a more porous structure in comparison with unmodified samples. Cerium cations are stabilized in the region of interblock boundaries or in the structural defects of rutile TiO2 and are released as the bulk CeO2 phase only at 1000 degrees C, which does not exert a stabilizing effect at this temperature.

Holes with an average size of 2–5 nm have been created in graphene layers by heating of graphite oxide (GO) in concentrated sulfuric acid followed by annealing in an argon flow. The hot mineral acid acts simultaneously as a defunctionalizing and etching agent, removing a part of oxygen-containing groups and lattice carbon atoms from the layers. Annealing of the holey reduced GO at 800 °C–1000 °C causes a decrease of the content of residual oxygen and the interlayer spacing thus producing thin compact stacks from holey graphene layers. Electrochemical tests of the obtained materials in half-cells showed that the removal of oxygen and creation of basal holes lowers the capacity loss in the first cycle and facilitates intercalation-deintercalation of lithium ions. This was attributed to minimization of electrolyte decomposition reactions, easier desolvation of lithium ions near the hole boundaries and appearance of multiple entrances for the naked ions into graphene stacks.

Co-crystals of pharmaceutical compounds are widely used to improve the properties of drug formulations, such as dissolution behavior, bioavailability, or tabletability. The main methods of their synthesis include co-crystallization from solution, melt, or cogrinding. Only a few examples have been documented when co-crystals have been obtained by freeze-drying, namely, in systems where the components of a target co-crystal had similar aqueous solubilities. This work illustrates the potential of freeze-drying for obtaining pharmaceutical cocrystals when the solubilities of individual components differ drastically. Co-crystals of a model system-meloxicam and succinic acid-could be obtained both as a pure crystalline phase and forming a solid dispersion with a polymeric carrier. We show that even for pharmaceutical compounds with very low aqueous solubility, co-crystals with well-soluble coformers can be successfully produced under well-optimized conditions of cooling and subsequent freeze-drying. The rate of release of meloxicam from the fine solid dispersion of its cocrystal with succinic acid in polyethylenglycol obtained by freeze-drying was significantly higher than dissolution rates of (a) pure meloxicam cocrystals with succinic acid obtained by different variants of freeze-drying (thin film freezing, TFF, and spray freeze-drying, SFD), (b) the powder of meloxicam co-crystal with succinic acid obtained by liquid-assisted cogrinding. The possibility to obtain co-crystals of components with very different aqueous solubilities not only by TFF or SFD techniques but also by freezing solutions in vials at temperatures significantly higher than that of liquid nitrogen is shown.

Проведена оценка возраста и скорости накопления донных отложений оз. Чеко, расположенного на юге Эвенкии на территории заповедника “Тунгусский”, вблизи предполагаемого эпицентра Тунгусской катастрофы 1908 г. Вертикальные распределения активностей 137Cs, 210Pb и визуальный подсчёт слоёв в керне донных отложений, отобранном в центре озера, свидетельствуют, что оз. Чеко существенно старше Тунгусской катастрофы 1908 г., поэтому не может быть кратером или следом взрыва, как это предполагали некоторые исследователи ранее.