X-ray analysis of multilayer In<Subscript>0.52</Subscript>Al<Subscript>0.48</Subscript>As/In<Subscript>0.53</Subscript>Ga<Subscript>0.47</Subscript>As/In<Subscript>0.52</Subscript>Al<Subscript>0.48</Subscript>As HEMT heterostructures with InAs nanoinsert in quantum well

In_0.52Al_0.48As/In_0.53Ga_0.47As/In_0.52Al_0.48As HEMT heterostructures on InP substrates with elastically strained InAs insert in combined quantum well (QW) have been investigated using a combination of X-ray methods: double-crystal X-ray diffraction, X-ray reflectivity, and reciprocal space mapping. This approach has provided detailed complementary information about the layered and real crystal structures of the samples. The data obtained have made it possible to perform structural analysis of the multilayer systems and compare their characteristics with specified technological parameters, due to which the HEMT growth technology can be corrected and improved.     

Production,Purification, and Study of the Amino Acid Composition of Microalgae Proteins

Microalgae are known to be rich in protein. In this study, we aim to investigate methods of producing and purifying proteins of 98 microalgae including Chlorella vulgaris, Arthrospira platensis, Nostoc sp., Dunaliella salina, and Pleurochrysis carterae (Baltic Sea). Therefore, we studied their amino acid composition and developed a two-stage protein concentrate purification method from the microalgae biomass. After an additional stage of purification, the mass fraction of protein substances with a molecular weight greater than 50 kDa in the protein concentrate isolated from the biomass of the microalga Dunaliella salina increased by 2.58 times as compared with the mass fraction before filtration. In the protein concentrate isolated from the biomass of the microalga Pleurochrysis cartera, the relative content of the fraction with a molecular weight greater than 50.0 kDa reached 82.4%, which was 2.43 times higher than the relative content of the same fractions in the protein concentrate isolated from this culture before the two-stage purification. The possibilities of large-scale industrial production of microalgae biomass and an expanded range of uses determine the need to search for highly productive protein strains of microalgae and to optimize the conditions for isolating amino acids from them.     

Fabrication of Multilayer Films on the Basis of Lysozyme Protein and Precipitant (Iodide and Potassium) Ions on a Silicon Substrate by the Modified Langmuir–Schaefer Method

Multilayer structures, consisting of successive lysozyme layers and layers of iodide and potassium ions, have been formed on a silicon substrate by the modified Langmuir–Schaefer method; the use of this technique implies preliminary preparation of a crystallization protein solution containing an oligomeric phase. The multilayer structure has been characterized by methods of X-ray reflectivity and total external reflection X-ray standing waves (TER XSW). The data obtained indicate the formation of a dense lysozyme film (3 nm thick) and layers of potassium and iodide ions, adjacent to this film.     

X-ray acoustic resonators for controlling the spatial characteristics of X-radiation

The paper presents the results of studying the acoustic characteristics of special X-ray acousto-optical elements designed for precision control of X-ray beam parameters with time resolution. X-ray measurements revealed a number of specific features of oscillations of X-ray acoustic elements not exhibited in standard electromechanical measurements. The existence of these features is confirmed by numerical calculations computations of the acoustic fields in this type of elements.     

Determination of cinnamic acid by capillary zone electrophoresis using ion-pair reagents

The behavior of cinnamic acid in the presence of ion-pair reagents has been studied. Conditions have been chosen for the selective determination of cinnamic acid by capillary zone electrophoresis with normal and reversed polarity and spectrophotometric detection; the results have been applied for the analysis of drinks and milk hydrolysates. The influence of surfactants (sodium dodecyl sulfate, sodium octyl sulfonate) present in the buffer electrolyte on the efficiency of cinnamic acid determination is discussed.     

Study of the structural quality of heteroepitaxial silicon-on-sapphire structures by high-resolution X-ray diffraction,X-ray reflectivity,and electron microscopy

Heteroepitaxial silicon-on-sapphire (SOS) structures have been studied by high-resolution X-ray diffraction, X-ray reflectivity, electron microscopy, and electron diffraction. These methods yielded a large amount of complementary data on the defect structure of both the sapphire substrate and the silicon film, including integral and local (at the atomic-resolution level) information about the substrate, film, and sapphire-silicon interface.     

Experimental Study of Two-Beam X-Ray Diffractometry Using Synchrotron Radiation

Crystallography Reports - A new scheme of two-beam X-ray diffractometry on the “X-Ray Crystallography and Physical Materials Science” (XCPM) beamline at the Kurchatov Synchrotron...     

X-ray Diffraction Analysis and Electron Microscopy of the Carbon Fiber Structure

Crystallography Reports - A technique for studying the carbon-fiber structure using X-ray diffraction and electron microscopy has been developed. Average crystal-structure parameters are determined...     

Features of X-ray diffraction on sapphire single crystals with a nanostructured surface

Single-crystal sapphire plates with stepped nanostructures on the surface produced by thermal treatment and with a stochastically distributed surface roughness were studied by X-ray diffraction. It was found that the angular dependencies of intensities and half-widths of the curves of diffraction reflection measured under the Bragg geometry conditions appreciably changed versus the mutual orientation of the direction of propagation of the X-ray beam and the position of the steps, forming nanostructures on the surfaces of sapphire plates.     

Lattice Parameter Local Determination for Trigonal,Hexagonal, and Tetragonal Crystal Systems Using Several Coplanar X-Ray Reflections

The method for determining the local lattice parameters using quasi-multiple X-ray diffraction (which was proposed and used only for crystals of the cubic system) has been expanded to measure the local crystal lattice parameters for the trigonal, hexagonal, and tetragonal systems. Local variations in the lattice parameters in the tetragonal paratellurite (TeO₂) and trigonal lanthanum-gallium tantalate (La₃Ga_5.5Ta_0.5O₁₄) crystals have been investigated. Reflections necessary for implementing the quasi-multiple X-ray diffraction scheme are found for these crystals. The pairs of reflections that were found were used to complete quasi-multiple X-ray diffraction schemes on a laboratory X-ray source and determine the variation in the lattice parameter a along the surface of these crystals. The relative measurement error was 4 x 10^-6 at a spatial resolution of 140 μm. The accuracy of the method and the parameters determining this characteristic were analyzed based on the results. The locality of the method and the limits of the spatial resolution of an X-ray diffraction measurement of lattice parameters are estimated.