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Moolooite, Cu(C2O4)·nH2O, is a typical biomineral which forms due to Cu-bearing minerals coming into contact with oxalic acid sources such as bird guano deposits or lichens, and no single crystals of moolooite of either natural or synthetic origin have been found yet. This paper reports, for the first time, on the preparation of single crystals of a synthetic analog of the copper-oxalate biomineral moolooite, and on the refinement of its crystal structure from the single-crystal X-ray diffraction (SCXRD) data. Along with the structural model, the SCXRD experiment showed the significant contribution of diffuse scattering to the overall diffraction data, which comes from the nanostructural disorder caused by stacking faults of Cu oxalate chains as they lengthen. This type of disorder should result in the chains breaking, at which point the H2O molecules may be arranged. The amount of water in the studied samples did not exceed 0.15 H2O molecules per formula unit. Apparently, the mechanism of incorporation of H2O molecules governs the absence of good-quality single crystals in nature and a lack of them in synthetic experiments: the more H2O content in the structure, the stronger the disorder will be. A description of the crystal structure indicates that the ideal structure of the Cu oxalate biomineral moolooite should not contain H2O molecules and should be described by the Cu(C2O4) formula. However, it was shown that natural and synthetic moolooite crystals contain a significant portion of “structural” water, which cannot be ignored. Considering the substantially variable amount of water, which can be incorporated into the crystal structure, the formula Cu(C2O4)·nH2O for moolooite is justified.

The breaking of inversion symmetry can enhance the multifunctional properties of layered hybrid organic–inorganic perovskites. However, the mechanisms by which inversion symmetry can be broken are not well-understood. Here, we study a series of MnCl4-based 2D perovskites with arylamine cations, namely, (C6H5CxH2xNH3)2MnCl4 (x = 0, 1, 2, 3), for which the x = 0, 1, and 3 members are reported for the first time. The compounds with x = 1, 2, and 3 adopt polar crystal structures to well above room temperature. We argue that the inversion symmetry breaking in these compounds is related to the rotational degree of freedom of the organic cations, which determine the hydrogen bonding pattern that links the organic and inorganic layers. We show that the tilting of MnCl6 octahedra is not the primary mechanism involved in inversion symmetry breaking in these materials. All four compounds show 2D Heisenberg antiferromagnetic behavior. A ferromagnetic component develops in each case below the long-range magnetic ordering temperature of ∼42–46 K due to spin canting., We study a series of MnCl4-based 2D perovskites with arylamine cations: (C6H5CxH2xNH3)2MnCl4 (x = 0, 1, 2, 3). The compounds with x = 1, 2 and 3 adopt polar crystal structures to well above room temperature. The inversion symmetry breaking in these compounds is driven by the rotational degree of freedom of the organic cations, which determine the hydrogen bonding pattern that links the organic and inorganic layers.

Cuban and Mexican zeolites are of particular interest from economic outlook because of their exceptional properties and abundance. Here, we present the results of the comparative study of the elemental, structural, morphological, thermal and textural properties of natural zeolites: clinoptilolite, mordenite and erionite from various deposits. Despite a complex phase and element compositions of the studied materials, some general features were detected. The observed dehydration steps are related to water desorption from porosity of different size ranges: mesopores, main and small zeolite voids. This dehydration pattern interferes with the exchangeable cation composition that also affects the general trends. Thermochemical properties of samples are influenced by the geographical location of the deposits. Depending on the origin of the sample, the dehydration enthalpy varies in quite a wide range, which is a function of both zeolite framework structure and exchangeable cation composition. The study of meso- and macropore systems reveals that all the samples exhibit multimodal pore size distribution and possess significant amounts of mesoporosity and even macroporosity. Among the studied samples, the mordenite from Palmarito de Cauto, the clinoptilolite from Etla and the erionite from Agua Prieta (Sonora) have a significant number of pores with average size of about 3 nm. All the samples, except erionite from Agua Prieta, show macroporosity with rather well-defined pore size between 0.3 and 2 μm. The porosity over mass does not change noticeably from one sample to other and varies from 0.32 to 0.65 cm3 g−1.

The effect of 1,1,9-trihydroperfluorononanol-1 immobilized on montmorillonite nanoclay on the nature of structural transformations and the properties of polycaproamide composites was studied. Using the methods of electron, atomic force microscopy and differential scanning calorimetry, we established the features of changing the diameter and height of spherulites in non-oriented films of this heterochain polymer, as well as the reorganization of its polymorphic composition due to the introduction of a fluorine-containing modifier. The stabilizing effect of the additive used on the mechanical properties and thermo-oxidative stability is shown.

The derivative of 1,2,4-thiadiazole (TDZ) can be considered as a perspective agent for the Alzheimer’s disease prevention. Due to a highly lipophilic character, the compound reveals good membrane permeability properties and poor solubility in aqueous media. In order to solve this problem, water-soluble biodegradable polymers: PEG 6000 (PEG), PVP K29-30 (PVP) and linear (A–B–A type) ethylene oxide-propylene oxide block copolymer Pluronic F127 (F127) were used in the present investigation to obtain binary and ternary TDZ composites (solid dispersions) with improved solubility and dissolution rate. Composites were prepared by a mechanical grinding procedure. Differential scanning calorimetry and FTIR spectroscopy were used to characterize the obtained samples. The interaction of TDZ with PVP after the grinding procedure was revealed. Shake-flask method was applied to measure the solubility of the composites. A dramatical increase in the solubility was shown for the solid dispersion with F127 above the critical micelle concentration. The dissolution behavior was studied with the help of the basket method at pH 1.2 and pH 6.8. The dissolution of TDZ/polymer solid dispersions was substantially accelerated as compared to pure TDZ and physical mixtures. The dissolution mechanism was estimated through the Korsmeyer–Peppas model equation. Franz diffusion cell and new Permeapad™ barrier were applied for the permeability assay. The permeability of TDZ in solid dispersions through the Permeapad™ barrier was shown to decrease in comparison with the pure TDZ. It was concluded that composites with PEG, PVP and F127 are an effective tool for increasing the solubility and dissolution of 1,2,4-thiadiazole derivative.

Using the data obtained by Knudsen effusion mass spectrometry, the standard formation thermodynamic properties of La2Hf2O7, Nd2Hf2O7, and Gd2Hf2O7 were calculated in the present study at high temperatures. Based on the results obtained, it was shown that the standard formation Gibbs energies of La2Hf2O7, Nd2Hf2O7, and Gd2Hf2O7 from the elements at the temperature 2445 K were consistent with the empirical rule concerning decrease of stability of pyrochlore hafnate phase with decrease in lanthanoid ionic radius. The La2Hf2O7 and Gd2Hf2O7 heat capacities were obtained in the present study by differential scanning calorimetry. These data were used along with those found earlier to evaluate the standard formation Gibbs energies of La2Hf2O7 and Gd2Hf2O7 from the elements at the temperature 298 K, which equal (−3937 ± 10) kJ/mol and (−3895 ± 10) kJ/mol, respectively. The thermodynamic properties of La2Hf2O7, Nd2Hf2O7, and Gd2Hf2O7 estimated in a wide temperature range allowed consideration of reliability of data available in the literature.

Blends of fly ash and natural calcite, mechanically activated for 0&ndash, 400 s in a planetary mill, were used to synthesize geopolymers at ambient temperature. The calcite content in the blends was 0&ndash, 10 wt.%. Sodium hydroxide solution was used as an alkaline agent. Mechanical activation of the raw material considerably enhanced its reactivity with respect to the alkaline agent, as was observed using Fourier-transform infrared spectroscopy, isothermal conduction calorimetry, thermogravimetry coupled with mass spectrometry analysis of the evolved gas, and SEM/EDS. The addition of calcite to the fly ash improved the compressive strength of the geopolymers, especially during the early age of curing. For 7 d aged geopolymers based on the 90% fly ash + 10% calcite blend, the strength was 8.0-, 3.5- and 2.9-fold higher than that for the geopolymers based on the unblended fly ash for 30 s, 180 s and 400 s mechanical activation time, respectively. Using M&ouml, ssbauer spectroscopy, it was revealed that iron present in the fly ash did not play a significant part in the geopolymerization process. The dominant reaction product was sodium containing aluminosilicate hydrogel (N-A-S-H gel). Calcite was found to transform, to a small extent, to vaterite and Ca(OH)2 in the course of the geopolymerization.

A lanthanum zirconate La2Zr2O7 was synthesized by soft mechanochemical method using zirconium oxynitrate ZrO(NO3)2·6H2O and lanthanum carbonate La2(CO3)3·8H2O as reagents. Mechanical activation of the reagents was carried out in a centrifugal planetary ball mill. The processes occurring during calcination of the jointly and the separately mechanically activated salt mixture were studied using DSC, TG coupled with mass spectrometry, XRD analysis, and FTIR spectroscopy. It was shown that in the course of joint mechanical activation in the mill alongside with intimate mixing of the reagents and their amorphization exchange reaction occurred, producing lanthanum nitrate, basic lanthanum nitrate, basic zirconium carbonate, and hydrated zirconium oxide. The DSC curve of the jointly mechanically activated salt mixture showed a strong exothermic peak at 878 °C which was not associated with mass loss. This peak was attributed to La2Zr2O7 crystallization in agreement with XRD data. Nanocrystalline lanthanum zirconate synthesized by annealing of the jointly mechanically activated salt mixture was characterized using XRD analysis, scanning, and transmission electron microscopy.

Reactions of layered perovskite-like oxides K2La2Ti3O10, NaLaTiO4 and corresponding protonated oxides H2La2Ti3O10, HLaTiO4 with vanadyl sulfate aqueous solution have been studied. It was revealed that the exchange reaction of interlayer alkali cations in K2La2Ti3O10 and NaLaTiO4 by with vanadyl cations, which was reported in the literature previously, does not proceed. The formation of the corresponding protonated forms and vanadium-containing particles is found to occur instead. In the case of protonated forms H2La2Ti3O10, HLaTiO4 vanadium-containing nanostructures are formed on the surface.

To find promising analogues of naturally occurring enediyne antibiotics with a sufficient reactivity in the Bergman cyclization and moderately stable under isolation and storage, a scale of relative enediynes reactivity was created on the basis of calculated free activation energies for the Bergman cyclization within 12 known and new benozothiophene, benzene, and cinnoline annulated 9- and 10-membered enediynes. To verify the predicted reactivity/stability balance, three new carbocyclic enediynes fused to a benzothiophene core bearing 3,4,5-trimethoxybenzene, fluoroisopropyl, and isopropenyl substituents were synthesized using the Nicholas-type macrocyclization. It was confirmed that annulation of a 3,4,5-trimethoxybenzene moiety to a 10-membered enediyne macrocycle imparts high reactivity to an enediyne while also conferring instability under ambient temperature. Fluoroisopropyl-substituted 10-membered enediyne from the opposite end of the scale was found to be stable while moderately reactive in the Bergman cyclization. Along with the experimentally confirmed moderate reactivity (DSC kinetic studies), (fluoroisopropyl)enediyne showed a significant DNA damaging activity in plasmid cleavage assays comparable with the known anticancer drug Zeocin.

This article is devoted to the investigation of water sorption by the layered perovskite-type titanate K2Nd2Ti3O10 and its intercalated protonated derivatives HxK2−xNd2Ti3O10·yH2O in a humid atmosphere. K2Nd2Ti3O10 was synthesized by the solid-state reaction. Metastable HxK2−xNd2Ti3O10·yH2O compounds were obtained by water flushing. The determination of the samples composition was carried out by XRD and TG analysis. The stability in a humid atmosphere was investigated by a water vapor sorption analyzer. It was found that humid atmosphere has influence only on K2Nd2Ti3O10 while HxK2−xNd2Ti3O10·yH2O phases are stable under experimental conditions. The study of K2Nd2Ti3O10 in humid atmosphere has shown that the intercalation process proceeds with a rate constant kint = 3.2 × 10−6 min−1 at 0–95% RH, and the protonation process takes place at RH more than 80%.

Cyclic organosilicon triperoxides were found to be vinyl-selective free-radical initiators for thermal curing at 100–180 °C of vinyl-terminated polydimethylsiloxane and trimethylsilyl-terminated polymethylhydrosiloxane producing homogeneous transparent silicone rubbers with antibacterial properties. The usage of the cyclic organosilicon triperoxides as the curing agents does not require free radical inhibitors in comparison with diacyl- and dialkyl peroxides. Among the tested compounds, the peroxide with the Me–Si–Me fragment and two cyclohexane rings is a much more active curing agent (180 °C, c = 0.22 M, τcuring = 45 min) than other organosilicon peroxides. Cured silicone samples from mixtures with vinyl-terminated polysiloxane and silicone hydride have improved mechanical properties: peroxides provide more than 200% elongation, and compression sets of the samples are less than 1%. The prepared silicone rubbers showed pronounced antibacterial activity.

This work is devoted to the preparation of zirconium oxide nanopowders stabilized by lanthanum oxide using the method of codeposition in the presence of hydrogen peroxide. Nanopowders composed of 0.97ZrO2 · 0.03La2O3 with particles of 10–20 nm are obtained. It is found that in the temperature interval of 500–1100°C the tetragonal and monoclinic points of the zirconium oxide phase crystallize at the same time.

Differential scanning calorimetry, thermogravimetry, and X-ray diffraction analysis were used to study the fundamental aspects of structural-chemical transformations occurring under the action of temperature in the range 50–1530°C in the system constituted by alumina core and phosphorus oxide shell synthesized by the molecular-layering method. It was shown that, as the P/Al molar ratio in the system increases from 0.05 to 0.14, the stability range of low-temperature forms of alumina extends to higher temperatures because crystalline aluminum phosphate is formed on the surface. It was demonstrated that using an inorganic binder based on a silicate binding agent and alumina modified with an aluminum phosphate layer provides a ~3.5-fold increase in the mechanical strength of the material at a ~5-fold decrease in the internal stress as compared with the composition with the unmodified oxide.

Bazhenov formation is the key kerogen-bearing oil shale reserve in Russia. Therefore, as recovery from conventional reservoirs decreases, the need to find enhanced oil recovery (EOR) techniques in order to develop Bazhenov formation becomes evident. Despite the huge amount of reserves, oil shales in Russia have not been developed extensively due to the absence of suitable recovery technique. High pressure air injection (HPAI) is one of the recovery techniques that has a potential to become the main recovery method. In order to design this method correctly, different aspects must be investigated. To do that, thermal analysis methods should be implemented. In this work, thermomicroscopy, simultaneous thermal analysis and open system pyrolysis were performed to investigate kerogen conversion process. The optical thermomicroscopy showed changes in the macrostructure and the morphology of the Bazhenov shale sample during heating up to 720 °C with the heating rate 10 °C/min. It was demonstrated that the conversion of kerogen into hydrocarbons caused increasing in sample porosity. Geometrical characteristics of pores such as size and shape were determined, dynamic events during the heating were investigated. During the air purge, intensive fracturing occurred along the voids formed due to oxidation of organic matter at 450 °C. The simultaneous thermal analysis (STA) revealed linear relationship between TOC and heat value for single well samples. Interval of oxidation reactions was determined. Bulk-kinetic parameters (activation energy and frequency factor) were calculated by numerical inversion of pyrolysis data using the Kinetics2015 optimization software. Fixing the A factor to a 2×1014 s−1 and using a spacing of 1 kcal/mole in the discrete activation energy distribution were investigated. In result, solution for different samples along the well was rather stable comparing to traditional approach.

Man-made deposits of fly ash (FA)—a solid by-product of coal combustion—accompany practically every thermal power station and many industrial plants. The total annual production of FA worldwide is about seven–eight hundred million tons, of which less than one third is recycled. The accumulated FA has become a problem for the environment due to its heavy metal content, which can be leached out. The mineral composition of FA is mainly represented by the glass phase and also by quartz, mullite, magnetite and other minerals. In the last decade, intensive studies have been carried out on the use of FA for the preparation of geopolymer materials. Due to their energy savings, environmentally friendly processing and high physical-mechanical properties, geopolymers are gaining attention in the construction industry as a potential replacement for Portland cement. In this work, we focused on the effect of natural dolomite addition to FA and mechanical activation of this blend on the geopolymerization process. The influence of dolomite dosage and duration of mechanical activation in a planetary mill on the reactivity of the blend in relation to NaOH solution and on the geopolymer compressive strength was studied.

A lanthanum zirconate (La 2 Zr 2 O 7 , LZ) precursor has been prepared by coprecipitation of the relevant hydroxides from nitrate solution. The effect of the mechanical activation of the precursor on its thermal decomposition and LZ formation in the temperature range of 700–1100 °C has been investigated. After mechanical activation, the precursor releases volatile components (H 2 O and CO 2 ) at lower temperatures. Mechanical activation accelerates the LZ crystallisation and results in the formation of phase-pure LZ without admixtures of unreacted zirconia and lanthana. The LZ powder prepared from the mechanically activated precursor is characterised by a larger BET surface area, in comparison to that synthesised from the as-prepared precursor under the same calcination conditions.

High-quality single crystals of perovskite-like (CH3NH3)3Bi2I9 hybrids have been synthesized, using a layered-solution crystal-growth technique. The large dielectric constant is strongly affected by the polar ordering of its constituents. Progressive dipolar ordering of the methylammonium cation upon cooling below 300 K gradually converts the hexagonal structure (space group P63/mmc) into a monoclinic phase (C2/c) at 160 K. A well-pronounced, ferrielectric phase transition at 143 K is governed by in-plane ordering of the bismuth lone pair that breaks inversion symmetry and results in a polar phase (space group P21). The dielectric constant is markedly higher in the C2/c phase above this transition. Here, the bismuth lone pair is disordered in-plane, allowing the polarizability to be substantially enhanced. Density functional theory calculations estimate a large ferroelectric polarization of 7.94 μC/cm(2) along the polar axis in the P21 phase. The calculated polarization has almost equal contributions of the methylammonium and Bi(3+) lone pair, which are fairly decoupled.

The article presents results of the complex study of hydration and protonation processes of promising photocatalysts K2Nd2Ti3O10, belonging to the family of perovskite-type layered Ruddlesden–Popper phases. K2Nd2Ti3O10 was synthesized by solid-state method and was monitored using powder X-ray diffraction. The behavior in water has been studied by means of thermogravimetric analysis, simultaneous thermal analysis and differential scanning calorimetry. The substitution of potassium cations for protons and the water intercalation into the interlayer space of the crystal structure were observed. Proton-containing layered oxides with general formula HxK2−xNd2Ti3O10·yH2O (0.07 ≤ x ≤ 1.7, 0.06 ≤ y ≤ 0.44) have been obtained.

Physicochemical properties of expanded vermiculite-phlogopite products from Kovdor (Murmansk region, Russia) used for 15 years as a hydroponics substratum were studied. The four investigated samples were as follows: natural vermiculite, initial expanded (roasted at 700 °C) vermiculite, spent expanded vermiculite and spent vermiculite roasted again at the same temperature. Data on the bulk density, field capacity, hygroscopicity, and expansion coefficients showed that the degradation of the substratum was accompanied by mechanical destruction, reduction of water absorption by half, and transformation of mineral phases. The structural transformation of expanded vermiculite was studied using X-ray diffraction (XRD), thermogravimetric analysis (TG), and differential scanning calorimetry (DSC), coupled with a mass spectrometric analysis of the released gases. Under conditions with a sufficient supply of plants with potassium of nutrient solution, a change in the mineral composition occurred: a decrease in the content of vermiculite and an increase in phlogopite. The formation of organomineral complexes on the surface of the vermiculite was detected. There was no noticeable change in the chemical composition of the expanded vermiculite during its use in hydroponics. In essence, the levels of potentially toxic elements (Mn, V, Ni, Cr, Co, Cu, Zn) met environmental regulations, and the levels of major elements (Mg, Ca, K, Fe, Mn) corresponded to those found in natural vermiculite. The chemical composition and structure of spent vermiculite allows its use as an ameliorant to improve soil, water, and air regimens.

Layered perovskite-type oxides A2Ln2Ti3O10 (A = Li, Na, K; Ln = La, Nd) prepared by solid-phase synthesis and their hydrated forms were characterized by the methods of TGA, XRD, and by UV-Vis spectroscopy. Photocatalytic activity of A2Ln2Ti3O10 oxides in reaction of hydrogen evolution from aqueous alcoholic suspensions irradiated by UV-light was studied. It was shown that the ability to intercalation of water into interlayer space essentially affects the rate of photoinduced hydrogen evolution and is a determining factor leading to a high photocatalytic activity.

The behavior in aqueous solutions of the two types of layered perovskite-like structures, NaLnTiO4 titanates (Ln = Nd, La) belonging to the family of Ruddlesden–Popper phases and ANdTa2O7 tantalates (A = Na, Cs, H) belonging to the family of Dion–Jacobson phases, has been studied by means of thermogravimetric analysis and powder X-ray diffraction. In the case of NaLnTiO4 compounds, the substitution of protons for sodium cations and the water intercalation into the interlayer space of the crystal structure were observed and proton-containing layered oxides with general formula H x Na1−x LnTiO4·yH2O (0.63

The behavior of perovskite-like NaNdTiO4 complex oxide in acid aqueous solutions was studied. By the X-ray and thermogravimetry analyses the instability of NaNdTiO4 in aqueous solutions was found, which is determined by the sodium cation exchange for protons and by water molecules intercalation into the interlayer space of the crystal structure. The proton-containing layered oxides HNdTiO4 and H x Na1−x NdTiO4·yH2O were obtained (1 < x < 0.64, 0 < y < 0.47). The structure of the H0.73Na0.27NdTiO4·0.3H2O compound was refined.

Separation of aqueous isopropanol solutions by pervaporation using membranes based on composites of a polyimide with an aniline-anthranilic acid copolymer was studied.

The processes of phase formation in the Na2CO3-TiO2 and Na2CO3-TiO2-Nd2O3 systems are investigated in the temperature range 600–900°C. The high-temperature solid-phase reactions underlying the process of formation of complex oxide NaNdTiO4 are studied. It is established that the synthesis of the NaNdTiO4 compound occurs through the reaction of the intermediate product Na8Ti5O14 with neodymium oxide in the temperature range 720–780°C. The optimum method is proposed for synthesizing NaNdTiO4, which makes it possible to reduce the temperature of the synthesis, to avoid the formation of impurities, and to obtain the product in a finely dispersed state.

Layered perovskite-type oxides ANdNb2O7 (A = Rb, Cs) were synthesised by the ceramic technique, ANdNb2O7 (A = Li, Na) - by ion exchange reaction in molten nitrates, and HNdNb2O7 - by ion exchange in an acid solution. These compounds were characterised by powder X-ray diffraction, TG analysis, UV-Vis diffuse reflection spectroscopy and scanning electron microscopy. Intercalation of water molecules into the interlayer space was detected only for NaNdNb2O7. Analysis of the photocatalytic activity was performed for photoinduced hydrogen evolution reaction from aqueous isopropyl alcohol. The highest photocatalytic activity was observed for RbNdNb2O7.