Том 63, № 6 (2018)

Proteinase K solutions have been investigated by small-angle X-ray scattering in the temperature range of 10–30°C under conditions of tetragonal crystal growth. Addition of ammonium sulfate or sodium nitrate as precipitants is shown to induce the formation of a significant fraction of protein dimers in solution (the dimer content in solution increases only slightly with a decrease in temperature). The structures of possible dimers, which form the pre-crystallization phase in solution (which is necessary for the growth of proteinase K crystals), have been investigated by analyzing the known crystal structure.

A criterion for estimating the homogeneity of materials for refractive X-ray optics from small-angle X-ray scattering data is proposed. A material of new type—nanoberyllium—is considered. A number of samples of beryllium materials, including commercial products, have been analyzed. The X-ray homogeneity of the materials is determined, as well as the influence of technological processes.

Thin-film samples of fluorides CaF₂, BaF₂, and LaF₃, free of oxyfluorides, have been fabricated by ultrasonic fragmentation (CaF₂) and sublimation in vacuum onto amorphous carbon substrates (BaF₂ and LaF₃). The electron diffraction patterns of these polycrystals are measured with a low statistical error (~1–2%) using an EMR-102 electron diffractometer. The reflection intensities were applied to refine the electronic structure; the refinement showed mainly ionic character of chemical bonding in these compounds. Electron density and electrostatic potential distributions were obtained using the parameters of kappa-model, which describes ionic bonding, and their quantitative analysis was performed within Bader’s topological approach. It is noted that the positions of “critical points” in the electrostatic potential and electron density maps for CaF₂, BaF₂, and LaF₃ crystals do not exactly coincide. This finding has confirmed the well-known fact: the electron density (and energy) of a many-electron system is not completely determined by the innercrystalline electrostatic field. The electron density and electrostatic potential maps supplement each other when describing interatomic interactions. A consideration of the gradient field E(r) = –∇φ(r) in these crystals confirms the conclusion that long-range Coulomb interactions of atoms (having finite sizes) occur in the form of atom‒ atom interactions. The interaction forces and their directions in crystal is a peculiar property of each compound (specifically, each structure type).

The crystal structure of aqualite from the Khibiny massif, a high-oxonium eudialyte-group mineral, has been refined by X-ray diffraction analysis using a set of low-temperature (110 K) experimental data. The trigonal-cell parameters are found to be a = 14.1435(4) Å, c = 31.410(1) Å, V = 5441.4(4) ų, sp. gr. R3m. The structure is refined to the final reliability factor R = 0.046 in the anisotropic approximation of atomic displacements using 1173F > 3σ(F). The idealized formula of the mineral (Z = 3) is (H₃O)₉Na₃ (K,Sr,Ba,Ce)₂Ca₆Zr₃Fe³⁺[Si₂₄O₇₂](OH,Cl,H₂O)₅. Low-temperature refinement explained the low symmetry of aqualite from the Inaglinskii massif and revealed some new structural features of the mineral. Oxonium occupies mainly the N1–N4 sites, partially the N5 void, and the N6 site. A unique feature of aqualite (and its Mn analog, ilyukhinite), which was not previously observed in eudialytes and is considered for the first time in this study, is the presence of inversely oriented complex anion, which significantly affects the N4 site occupancy.

Bis-hexaaquasodium decaaqua-monohydrogen-hexasodium-terbium(III)-bis-(nitrilo-tris-methylenephosphonate) hexahydrate has been synthesized, and its crystal structure has been determined (sp. gr. P2₁/с, Z = 2). The terbium atom occupies the center of a cage consisting of two phosphonate ligand molecules, connected by six inorganic P–O–Na–O–P bridges, and a coordination polyhedron. The latter is an almost regular rhombohedron; two of its vertices, distant from the center, contain nitrogen atoms of two organic ligand molecules, and the other six vertices are occupied by oxygen atoms belonging to different PO₃ groups. The complex contains six five-membered chelating cycles Tb–O–P–C–N, six eight-membered cycles Tb–O–P–C–N–C–P–O, and six heterometallic cycles O–Tb–O–Na.

The title molecular salts (C₅H₉N\(_{4}^{ + }\))(C₅H₈N₄)(C₇H₅O\(_{3}^{ - }\)) (I) and (C₅H₉N\(_{4}^{ + }\))(C₈H₅O\(_{4}^{ - }\)) (II) have been synthesized and characterized by single crystal X-ray diffraction, FT-IR and Hirshfeld surface analysis. I crystallizes in monoclinic system, sp. gr. P2₁/c, Z = 4. II crystallizes in triclinic system, sp. gr. P\(\bar {1}\), Z = 2. Both crystal structures are stabilized by N–H···O, N–H···N, O–H···O hydrogen bonds and weak π–π stacking interactions and form a ring motifs (\(R_{2}^{2}\)(8)) containing N⁺–H···O^– charge-assisted hydrogen bonds. FT-IR spectra confirm the presence of the functional groups in the synthesized compounds. Hirshfeld surface analysis was employed in order to study intermolecular interactions.

A cariprazine, an oral atypical antipsychotic acting as a D2 and D3 receptor partial agonist, has been crystallized as a free base, trans-N-{4-[2-[4-(2,3-dichlorophenyl)piperazine-1-yl]ethyl]cyclohexyl}-N',N'-dimethylurea, C₂₁H₃₂Cl₂N₄O (I), and as a chloride salt, trans-N-{4-[2-[4-(2,3-dichlorophenyl)piperazine-1-yl]ethyl]cyclohexyl}-N',N'-dimethylurea hydrochloride, C₂₁H₃₃Cl₂N₄O⁺Cl^– (II). In both structures, the cariperazine molecule is in an extended conformation. The dimethylurea group exhibits a syn conformation of the O atoms in the I, whereas an almost anti orientation is present in the II. Two terminal groups, dimethylurea and dichlorophenyl ring, are oriented differently in the I and II. The cariprazine molecules in the I are linked into an infinite zigzag chains by N–H···O hydrogen bonds, where the neighboring cariprazine molecules form an L-shape configuration. In the II, the molecules of cariprazine are connected with the chloride anion by N–H···Cl charge-assisted hydrogen bonds, which are further stabilized by weak intermolecular interactions, forming horizontal molecular chain along the b axis. This study reveals the variations in the solid-state conformation of cariprazine molecule in different crystalline environments.

A Ni(II) complex, [Ni(pydca)(bim)₃] (pydca = pyridine-2,6-dicarboxylate, bim = benzimidazole) has been prepared by hydrothermal synthesis. It is characterized by elemental analysis, IR and thermal analysis. The crystal structure is determined by single crystal X-ray diffraction. The mononuclear complexes are linked by N–H···O hydrogen bonds. The title complex has good thermal stability and exhibits good fluorescence properties in ethanol solution at room temperature.

The dynamics of octamers of two types, which form (via translation) a tetragonal lysozyme crystal lattice, has been simulated on a 100-ns path with and without a precipitant. It is shown that one of the octamers under study is stable in the presence of a precipitant, whereas the other octamer dissociates into components both in the presence and in the absence of a precipitant. The results obtained not only confirmed the results of previous measurements of lysozyme solutions with NaCl precipitant by small-angle X-ray neutron scattering but also made it possible to establish the type of the octamer forming in the crystallization solution.

Bacterial nanocellulose (BNC) samples were produced by the symbiotic culture Мedusomyces gisevii Sa-12 in synthetic nutrient medium and enzymatic hydrolysates of chemically treated oat hulls and studied by X-ray diffraction. The structural characteristics of the crystalline component of BNC samples were determined. A comparison of the X-ray diffraction patterns recorded in reflection and transmission geometry shows that the samples have an anisotropic structure. All BNC samples are characterized by a high degree of crystallinity (from 86 to 93%) and are mainly composed of the low-symmetry metastable phase Iα (its fraction is 93.6–100%). The Мedusomyces gisevii Sa-12 culture was found to produce highly crystalline BNC, with the low-symmetry phase Iα prevailing, regardless of the composition of the nutrient medium.

The dependence of the microhardness of KDP crystals with embedded TiO₂ nanoparticles on the time passed after their exposure to a dc magnetic field has been analyzed. Samples cut from different growth sectors are found to be differently affected by magnetic treatment. In the absence of TiO₂ impurity, the microhardness of the samples from the {100} growth sector decreases after the magnetic exposure, whereas the microhardness of the samples cut from the {101} growth sector changes in two stages (hardening after softening). With an increase in the TiO₂ concentration, the softening stage gradually disappears in the crystals from both growth sectors. In the KDP:TiO₂ crystals from the {100} sector, hardening (which was absent previously) occurs instead of softening. In the crystals from the {101} sector, the hardening arises after a shorter time.

Magnetophotovoltaic effect in piezoelectric crystals is considered for linearly and circularly polarized light. The influence of crystal’s optical activity and spin-photovoltaic effect on magnetophotovoltaic effect is analyzed.

The electrooptics in the bidirectional field switching mode in a homeotropically aligned layer of a nematic liquid crystal with two pairs of interdigitated microelectrodes situated on the opposite sides of the cell has been studied in detail. The method of bidirectional field switching eliminates the slow stage of free relaxation of liquid crystal (LC) molecules and makes it possible to approach a submillisecond speed of electro-optical switching. The electro-optical characteristics studied in the geometry with parallel interdigitated electrodes are compared with the previously obtained data for a cell with mutually orthogonal electrodes.

Specific features of light transmission and electroabsorption in a plasmonic nanostructure with organic semiconductor (zinc phthalocyanine, ZnPc) and subwavelength aluminum grating (Al^Gr) have been experimentally investigated. The glass–Al^Gr–ZnPc–Al nanostructure was prepared using layer-by-layer deposition. First, only a part of the structure has been analyzed to check the grating quality. After deposition of an organic semiconductor (ZnPc) layer on the grating, the transmission of TE and TM polarized light through Al^Gr and ZnPc layers upon excitation of plasmon resonances has been studied. Afterwards, a semitransparent aluminum layer has been deposited on the ZnPc layer (an additional electrode for measuring the electroabsorption effect). For TM polarized light, a multiple increase in the electroabsorption effect has been found (in comparison with a structure without subwavelength grating). This result can be explained by the Stark effect on exciton transitions and the presence of two cavities in the structure, which are related to the excitation of plasmonic states and the Fabry–Perot effect between aluminum electrodes. The presence of the cavities leads to a decrease in the group velocity of light and, accordingly, increases the density of exciton states, which are characterized by a large difference between polarizabilities in the excited and ground states.

The formation of graphene–iron composite structures on the surface of cleavages of silicon carbide single crystals using vacuum thermal destruction with simultaneous deposition of iron atoms has been investigated. The effect of the iron deposition rate on the formation of single- and multilayer graphene structures is established. It is shown by X-ray photoelectron and Raman spectroscopy that iron partially dissolves in the graphene structures without formation of nanocrystallites, clusters, etc.

Nanostructured spherical calcium carbonate particles with average sizes of 3.8 µm and 550 nm have been fabricated. Optimal conditions for adsorption of central anesthetic loperamide on these particles are found. The influence of particle size on the adsorption efficiency is studied. The efficiency of micron and submicron vaterite particles as carriers for intranasal loperamide delivery is compared using in vivo tests on laboratory animals.

Potassium cobalt sulfate hexahydrate (K₂Co(SO₄)₂ · 6H₂O, KCSH) crystals have been grown at a supersaturation σ in the range of 2–8.1%. The optimal conditions for KCSH crystal growth are refined by reducing the solution temperature. The real structure of crystals and their optical properties are investigated.

A series of three-component isostructural fluorite crystals (Sr_1–xBa_x)_0.7La_0.3F_2.3 (sp. gr. \(Fm{\bar {3}}m\), 0 ≤ x ≤ 1), the compositions of which belong to the Sr_0.7La_0.3F_2.3–Ba_0.7La_0.3F_2.3 polythermal section in the SrF₂–BaF₂–LaF₃ system, has been grown for the first time by vertical directional crystallization. Optical, mechanical, and electrical properties of three-component (Sr_1–xBa_x)_0.7La_0.3F_2.3 and two-component M_0.7La_0.3F_2.3 (M = Sr or Ba) crystals have been investigated and subjected to comparative analysis. It is shown that all three-component crystals (Sr_1–xBa_x)_0.7La_0.3F_2.3 are promising optical design materials.

Among the important antiquities of Altai Bronze Age, Karakol burial site (dated to the beginning of the 2nd mill. BCE) can be selected. The images are overlapped; the ones synchronous to the burial ritual were performed in a complex technique, including painting, pecking, engraving, and abrasion. Studies at the National Research Centre “Kurchatov Institute” (NRC KI), including scanning electron microscopy combined with X-ray microanalysis and powder X-ray diffraction on the Belok station (Kurchatov synchrotron radiation source (KSRS)), revealed that red (ochres of different hues) and black (soot) pigments were used to to produce paint at the Karakol site. An analysis of the red paints showed their composition to be homogeneous within one burial but differ from burial to burial. An analysis of the colored line on slab 1 (Karakol, burial 3, mound 2) made it possible to establish its natural origin and reasonably reject the hypothesis that it was painted.

The results of studying the monetary alloys of ancient Bosporos by X-ray fluorescent spectroscopy are presented. A change in the sources of silver for early Bosporos coins in the middle of the 5th century B.C. and a transition from presumably Thracian to Attic (Lavrion) source of silver supply are revealed. The deterioration of metal of Bosporan staters of the first centuries A.D. and their transformation from coins of “full metal value” into coins of conditional value has been studied in detail. Using the knowledge about the monetary alloy composition, one can analyze the financial and economic history of Bosporos, as well as its political, economic, trade, cultural, and technological influences and relations with the ancient centers of the Black Sea and Mediterranean regions.

Unique methods for processing diffraction data, which guarantee extreme accuracy and reliability, have been implemented in the ASTRA 4.0 software package. The central (data-forming) element is a program for averaging intensities of repeated and equivalent reflections. The ASTRA averaging algorithm makes it possible to calculate the average intensity and its standard uncertainty, which correspond to normal distribution law for errors in data. Such data yield an unbiased estimate of the parameters of refined structural model at minimum reliability factors. To make the averaging program successfully operate, one must introduce all corrections for anisotropic effects into the reflection’s intensities. The following stages of investigation are considered: sample preparation; calibration of diffractometer; and correction for absorption, thermal diffuse scattering, and simultaneous reflections. A significant advantage of the proposed approaches is proven on several examples.

The design of a new automatic X-ray microtomograph is described. The parameters of optical schemes and X-ray detectors in use are presented. Methods for automating experiments, processing tomographic data, and getting access to them are reported.