Vol 63, No 6 (2018)
- Year: 2018
- Articles: 34
- URL: https://journals.rcsi.science/1063-7745/issue/view/12128
Diffraction and Scattering of Ionizing Radiations
Investigation of the Pre-crystallization Stage of Proteinase K in Solution (Influence of Temperature and Precipitant Type) by Small-Angle X-Ray Scattering
Abstract
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.
Shape Determination of Bovine Fibrinogen in Solution Using Small-Angle Scattering Data
Abstract
A 3D model of the shape of bovine fibrinogen, one of the proteins responsible for blood coagulation, is constructed based on small-angle X-ray scattering (SAXS) data on bovine fibrinogen in solution, and the oligomeric composition of fibrinogen in solution is estimated. It is shown that fibrinogen molecules form elongated vermicular structures with a length on the order of 50 nm and an effective cross section of about 10 nm. The volume of these particles correlates well with the volume of two fibrinogen dimers. The results obtained may be helpful when applying fibrinogen and its modifications in tissue engineering.
A Study of Beryllium-Based Materials and Comparison of Their X-Ray Homogeneities According to Small-Angle Scattering Data
Abstract
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.
Crystal Chemistry
Electronic Structure and Electrostatic Potential Distribution in Nanocrystals of Fluorides CaF2, BaF2, and LaF3 According to Electron Diffraction Data
Abstract
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).
Structure of Inorganic Compounds
New Data on the Isomorphism in Eudialyte-Group Minerals. II. Refinement of the Aqualite Crystal Structure at 110 K
Abstract
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) Å3, 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.
Pb8K1.68Na0.32[(Ge0.65Si0.35)2O7]3—a Silicogermanate Analogue of the Mineral Nasonite
Abstract
Crystals of new silicogermanate Pb8K1.68Na0.32[(Ge0.65Si0.35)2O7]3 were synthesized under hydrothermal conditions in the PbO–SiO2–GeO2 system. The new compound is a synthetic variety of the diorthosilicate mineral nasonite Pb6Ca4[Si2O7]3Cl2 related to apatite. The hexagonal unit cell parameters are a = 10.1822(3) Å, c = 13.4088(5) Å, sp. gr. P63/m. The crystal structure was determined by direct methods using the SHELX program package and refined to R = 0.0647 based on 975 reflections with I ≥ 1.96σ(I). The new compound is characterized by wide isomorphism. The Ge and Si atoms occupy a tetrahedral site, and the K and Na atoms share a large-cation site. The main difference between the new compound and nasonite is that all Ca sites in the new compound are occupied by Pb, K, and (K,Na) atoms, and the tetrahedral site is mainly occupied by Ge. In nasonite the channels are filled by Cl anions that compensate the positive charge, whereas these channels are empty in the new synthetic variety. The presence of a large lead cation at the site occupied by Ca in nasonite causes structure distortion and changes in the coordination polyhedra. The umbrella-like coordination of the lead atom at the Pb1 site provides additional space for the lone pair of the Pb atom in the empty channel of the crystal structure; however, the crystals are centrosymmetric and, consequently, exhibit no nonlinear-optical properties.
Structure of Organic Compounds
Bis-hexaaquasodium Decaaqua-monohydrogen-hexasodium-terbium(III)-bis-(nitrilo-tris-methylenephosphonate) Hexahydrate [TbNa6H(H2O)10{N(CH2PO3)3}2] [Na(H2O)6]2 · 6H2O
Abstract
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.
Molecular and Crystal Structure of the Cocrystal of p-n-Heptyloxybenzoic Acid‒p-n-Hexyloxybenzoic Acid, Obtained in the System of Mesomorphic Acids
Abstract
The structure of the p-n-heptyloxybenzoic acid–p-n-hexyloxybenzoic acid crystal, obtained in the dual system of homologues of p-n-alkyloxybenzoic acids exhibiting mesomorphic properties has been studied by X-ray diffraction analysis at a temperature of 120 K. The crystals are triclinic, sp. gr. P\(\bar {1}\), a = 4.6380(7) Å, b = 8.0158(12) Å, c= 17.673(3) Å, α = 81.019(7)°, β = 85.632(7)°, γ = 76.935(7)°, Z = 2. The molecules in the cocrystal are combined in dimers by hydrogen bonds. The probability and conditions of the formation of cocrystals of the 1 : 1 and 1 : 2 compositions in such systems are discussed.
Synthesis, Crystal Structure, FT-IR Spectral Studies and Hirshfeld Surface Analysis of 3-Amino-5,6-dimethyl-1,2,4-triazine/3-Amino-5,6-dimethyl-1,2,4-triazinium-2 2-hydroxybenzoate and 3-Amino-5,6-dimethyl-1,2,4-triazinium-2 hydrogen phthalate
Abstract
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.
Crystal Structure of 2-(Hexyloxy)benzo[b]phenazine-6,11-dione
Abstract
Cyclization of 2-chloro-3-((4-(hexyloxy)phenyl)amino)naphthalene-1,4-dione obtained from the reaction of 2,3-dichloro-1,4-naphthoquinone with 4-(hexyloxy)aniline by sodium azide in N,N-dimethylformamide (DMF) at 90–95°C gives 2-(hexyloxy)benzo[b]phenazine-6,11-dione. This is a remarkable example of a general procedure to prepare functionalized benzo[b]phenazine-6,11-dione derivatives. The structure of the title compound was confirmed by single crystal X-ray diffraction analysis. The compound, C22H20N2O3, crystallizes in the sp. gr. P\(\bar {1}\), Z = 2. Both O atoms and one of N atoms are involved in hydrogen bonds forming a network. Besides, there is offset stacking interaction between the planes of polycyclic systems with interplanar distance of 3.383 Å.
Crystal Structures and Thermodynamic Properties of New Atypical Antipsychotic Cariprazine and Its Hydrochloride
Abstract
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.
Synthesis and Single Crystal X-Ray Structure of 3,5-Diphenyl-1-(phenylacetyl)-4,5-dihydro-1H-pyrazol
Abstract
The molecule of the title pyrazole derivative, 3,5-diphenyl-1-(phenylacetyl)-4,5-dihydro-1H-pyrazol, C23H20N2O, is twisted. The compound crystallizes in the monoclinic sp. gr. I2/a with a = 15.3502(13) Å, b = 12.7576(8) Å, c = 19.625(2) Å, β = 106.639(7)°, and Z = 8. In the compound, the phenyl rings form dihedral angles of 12.01(13)°, 80.36(8)°, and 86.95(9)° with the mean plane of the pyrazole ring (r.m.s. deviation = 0.030 Å). The central pyrazole ring, which approximates an envelope conformation, is almost coplanar with one of the phenyl rings. The crystal packing is stabilized by weak intermolecular C–H···O hydrogen bonds.
Nickel(II) Coordination Complex Constructed from Benzimidazole and Pyridine-2,6-dicarboxylate Co-ligands: Synthesis, Crystal Structure, Thermal Behavior, and Photoluminescence
Abstract
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.
Structure of Macromolecular Compounds
Study of the Behavior of Lysozyme Oligomers in Solutions by the Molecular Dynamics Method
Abstract
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.
Preliminary X-ray Diffraction Study of Macrophage Migration Inhibitory Factor at Near-Atomic Resolution
Abstract
Crystals of human macrophage migration inhibitory factor in complexes with phenyl isothiocyanate and tartrate were grown by the capillary counter-diffusion method under microgravity conditions. The preliminary X-ray diffraction study of these complexes was performed at near-atomic resolution (1.16 Å).
X-ray Diffraction Study of Bacterial Nanocellulose Produced by the Medusomyces gisevii Sa-12 Culture in Enzymatic Hydrolysates of Oat Hulls
Abstract
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.
Physical Properties of Crystals
Magnetostimulated Changes in the Microhardness of KDP Crystals with Embedded TiO2 Nanoparticles
Abstract
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.
Determination of the Optical Parameters of Uniaxial Optically Active Crystals Taking into Account the Imperfection of Spectrophotometric Complex Elements
Abstract
The influence of the imperfection of optical elements of a spectrophotometric system on the polarization transmission spectra of a uniaxial optically active absorbing plate has been analyzed by the example of a La3Ta0.25Ga5.25Si0.5O14 crystal, belonging to the langasite family. A comparison of the calculated and experimental transmission spectra for two samples with different thicknesses and optical-axis orientations shows that the optical-activity parameters of a crystal and the angle of deviation of the optical axis from the normal (when this angle is small) can be estimated.
Liquid Crystals
Submillisecond Electro-Optical Response of a Nematic Liquid Crystal in the Bidirectional Field Switching Mode
Abstract
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.
Surface and Thin Films
Features of Light Transmission and Stark Effect in a Plasmonic Nanostructure Comprising Organic Semiconductor and Subwavelength Aluminum Grating
Abstract
Specific features of light transmission and electroabsorption in a plasmonic nanostructure with organic semiconductor (zinc phthalocyanine, ZnPc) and subwavelength aluminum grating (AlGr) have been experimentally investigated. The glass–AlGr–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 AlGr 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.
Influence of Dye Molecules on the Polarization of Ferroelectric Vinylidene Fluoride Copolymer
Abstract
Electrical, electromechanical, and structural–optical properties of films of vinylidene fluoride copolymer with tetrafluoroethylene TFE, doped with Rhodamine 6G dye, have been investigated. It is found that the conductivity increases in doped films; at the same time, it “anomalously” decreases with an increase in the field. The hysteresis loop of local piezoelectric response has an asymmetric shape, which is related to the difference in the local field when its polarity changes. According to the data of absorption and luminescence spectra, the dye (at chosen concentrations) exists in form of, at least, monomers and dimers. It is shown by IR spectroscopy that hydrogen bonds can be formed between a dye molecule and vinylidene fluoride units located in amorphous regions. A model is formulated, which provides a correlation between the electrical and structural properties of the doped films.
Nanomaterials and Ceramics
Formation of Nanocomposites on the Surface of Silicon Carbide Crystals under Impact of Iron Fluxes
Abstract
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.
UV-Sensitive Porous ZnO-Based Nanocrystalline Films
Abstract
Nanocrystalline porous ZnO films have been synthesized by thermal oxidation of amorphous zinc deposits with an anomalously developed surface, which were previously formed using magnetron sputtering. The microstructure, morphology, phase composition, and optical properties of the synthesized oxide films have been studied by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and spectrophotometry. Applicability of the two-stage technique to fabrication of porous ZnO films for UV detectors is demonstrated.
Comparison of the Structural Features of Micron and Submicron Vaterite Particles and Their Efficiency for Intranasal Delivery of Anesthetic to the Brain
Abstract
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.
Crystal Growth
The Study of KCSH Crystals Grown from Aqueous Solutions by Accelerated Technique
Abstract
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.
The Study of Phase Equilibria in the Cs2SO4–Rb2SO4–H2SO4–H2O System
Abstract
The phase equilibria in the quaternary water–salt system Cs2SO4–Rb2SO4–H2SO4–H2O have been studied. The crystallization ranges are determined, and single crystals of (Cs1 – xRbx)2SO4 and Cs1 – xRbxHSO4 solid solutions have been grown. The (Cs1 – xRbx)3H(SO4)2 and (Cs1 – xRbx)5H3(SO4)4 · yH2O compounds are obtained for the first time.
Growth of Fluorite Solid Solution Crystals in the Ternary SrF2–BaF2–LaF3 System and Investigation of Their Properties
Abstract
A series of three-component isostructural fluorite crystals (Sr1–xBax)0.7La0.3F2.3 (sp. gr. \(Fm{\bar {3}}m\), 0 ≤ x ≤ 1), the compositions of which belong to the Sr0.7La0.3F2.3–Ba0.7La0.3F2.3 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 (Sr1–xBax)0.7La0.3F2.3 and two-component M0.7La0.3F2.3 (M = Sr or Ba) crystals have been investigated and subjected to comparative analysis. It is shown that all three-component crystals (Sr1–xBax)0.7La0.3F2.3 are promising optical design materials.
Synthesis of New SrPb3Br8 Crystals and Investigation of Their Properties
Abstract
A new compound, SrPb3Br8, has been synthesized and investigated by X-ray diffraction and spectroscopic methods. Its crystal structure is described as follows: Pnma, a = 8.0056(4) Å, b = 4.7359(2) Å, and c = 9.5208(5) Å. The crystals are transparent at wavelengths larger than ~360 nm; their band gap is 3.20 eV and the density is 6.242 g/cm3.
Crystallographic Methods in Humanitarian Sciences
The Composition of Paints of the Paintings on Stone Cist Slabs from Karakol (Altai)
Abstract
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.
Study of the Gilding Technology of the “Idol” from the 10th Century Mound “Chernaya Mogila” (“Black Grave”)
Abstract
A unique artifact—the “idol” from the 10th century mound “Chernaya Mogila” (“Black Grave”), a famous Old Rus’ site, has been studied. The technological features of the “idol’s” manufacture and decoration are revealed by studying the elemental composition of the metal substrate and surface layer of this object. The investigation has been performed by scanning electron microscopy with application of energy-dispersive X-ray microanalysis, X-ray fluorescence integral analysis, and inductively coupled plasma mass spectrometry. Based on the data obtained, it is concluded that the “idol” surface was gilded using amalgamation technology.
Evolution of the Composition of Monetary Alloys of Ancient Greek States on the Black Sea Shores Based on the Data of X-Ray Fluorescent Spectroscopy with the Example of Bosporos Cimmerian
Abstract
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.
Crystallographic Software and Apparatus
ASTRA 4.0 Program: Data Reduction for Obtaining Structure Results of Extreme Accuracy
Abstract
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.