Study of the Influence of a Precipitant Cation on the Formation of Oligomers in Crystallization Solutions of Lysozyme Protein

Crystallography Reports - The influence of the precipitant cation type in a series of chlorides (NaCl, KCl, LiCl, NiCl2, CuCl2, CoCl2) on the structure of lysozyme solutions has been investigated...     

Accurate Control of Synchrotron Radiation Parameters Using X-ray Acoustic Longitudinal Resonators: Paratellurite (ТeO2) Crystals

Crystallography Reports - When carrying out experiments on the P23 beamline of the Petra III synchrotron source (Hamburg, Germany), high efficiency of X-ray acoustic longitudinal resonators for...     

Selectivity of the optical-absorption method based on an instrumental pick out of Fourier components in the absorption spectrum

The introduction of interference–polarization filters (IPFs) in the structure of an optical–absorption analyzer makes it possible to pick out a harmonic (a Fourier component of the absorption spectrum) providing measurement with the highest sensitivity. The selectivity of such a method of analysis is determined by overlapping the oscillations of the measured and interfering components. By the example of measurement in benzene in the presence of an interfering component (toluene), the possibility is considered for the optimization of selectivity due to the variation of the path-difference dispersion for ordinary and extraordinary interfering rays. The metrological characteristics of the interference–polarization analyzer of C₆H₆ confirming the results of calculations are given.     

Erratum to: Effect of the Simulation Box Size and Precipitant Concentration on the Behavior of Tetragonal Lysozyme Dimer

Crystallography Reports - An Erratum to this paper has been published: https://doi.org/10.1134/S1063774521070282     

Growth and piezoelectric characterisation of GeO2 single crystals with quartz structure

Abstract

The first results for growth of germanium dioxide single crystals with the crquartz type structure (α-GeO₂) from refluxed hydrothermal solutions are reported. The success of this method is due to the existence of metastable α-GeO₂ in aqueous solutions at relatively low temperature and to the structural similarity between α-GeO₂ and α-SiO₂. The continuous partial evaporation of the heated solvent, vapour condensation, saturation of the condensate by nutrient α-GeO₂ and growth of α -GeO₂ single crystals on quartz seeds are considered as the successive stages of the process. Mzre homogeneous crystals of α -GeO₂ were obtained on seeds parallel to {0001}, {1120} and {1121} faces using sodium hydroxide and ammonium fluoride solutions in the range of temperature 90-130°C and at pressure equivalent to the fugacity of saturated vapor.

Piezoelectric, elastic and dielectric properties of the mentioned above crystals for the first time were studied.     

Dynamic variation in the lattice parameter of a crystal under ultrasonic treatment in X-ray diffraction experiments

The X-ray diffraction in the Laue geometry is investigated in germanium and silicon single crystals upon excitation of long-wavelength ultrasonic elastic strain waves traveling along the sample surface. The X-ray diffraction beam is bounded by a slit 0.2 mm in size, which is considerably less than the wavelength of the ultrasonic wave. The use of this slit makes it possible to separate crystal regions with a nearly homogeneous strain. As a consequence, the rocking curves stroboscopically measured in a double-crystal dispersionless scheme at different instants of time almost coincide with those for a perfect crystal with a lattice parameter varying in time. The rocking curves measured in a time-integrated mode turn out to be broadened, but their integrated intensities remain unchanged. Possible applications of the developed method are discussed.     

Separation of the Mechanisms of Photoinduced Deformations in Crystals Using Time-Resolved X-ray Diffractometry

Crystallography Reports - A diversity of effects leading to deformation of illuminated crystals has been mentioned. A methodical approach to studying the processes of generation of photoinduced...     

Study of the defect structure of paratellurite crystal using multiwave diffraction and normal X-ray diffractometry methods

Multiwave X-ray diffraction has been used to study the structure of crystalline samples. A cycle of local measurements of rocking curves (RCs) of the (220) and (371) reflections under conditions of multiwave diffraction (MD) has been carried out in a paratellurite crystal. The data obtained are used to compare the sensitivity to structure defects of two-beam diffraction with that of MD, which makes it possible to study the X-ray wave phase. The comparison has revealed a higher ability of the phase-sensitive method to detect defects.     

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.