High-resolution transmission electron microscopy (HRTEM) has shown regions of crystallites within noncrystalline matrices of three types of glass (volcanic glass, alkalic igneous glass, and synthetic, nuclear-waste-form glass) The volcanic glass fragments showed domains having 3-Å spacings. About 30% of the fragments of this glass showed localized lattice images, having spacings of 5, 7, 8, 10, 13, 14, 16, 19, and 20 Å, which also contain regular fringes having 3.3-Å separations. In the alkalic igneous glass fragments 3-Å domain structures were also noted as were localized lattice images having 7- and 12.5-Å spacings. Well-developed hollow spheres of primitive clays were present in both the volcanic and alkalic igneous glasses. Synthetic, nuclear-waste-foTm glass, fused at 1400°C and annealed at 550°C, showed locally ordered regions having 3.3-Å spacings. Low-angle X-ray powder diffraction showed major reflections at 8.5, 15–16, and 19 Å, which agree with some of the HRTEM measurements. These observations of domain structures, localized lattice images, primitive clays, and 14-Å clays in such noncrystalline glass matrices may contribute to an understanding of the growth of clay minerals. Such domains can apparently trigger the growth of clay products on the glass substrate.

X-ray diffraction (XRD) pattern of nanosized equimolar solid solution CoIr prepared by thermolysis of [Co(NH3)6][Ir(C2O4)3] contains peaks characteristic of both face-centered cubic (fcc) and hexagonal close-packed (hcp) structure. Moreover, 101 peak of hcp modification is substantially wider than 100 and 002 peaks, 102 and 103 are very broad and almost invisible. Peak 200 of fcc structure is wider than the other peaks of this modification and slightly shifted toward lower angles. It was shown by simulation of XRD patterns that particles of CoIr alloy are nanoheterogeneous and consist of lamellar domains having fcc and hcp structures. The best fit was obtained for the following model parameters: an average crystallites size is about 10 nm, average thicknesses of the fcc and hcp domains are 1.7 and 1.1 respectively. The presence of domain structure was confirmed by transmission electron microscopy data.

Monte Carlo domain structure simulation and Debye equation calculation of XRD patterns were used to confirm the formation of domain structure and investigate its peculiarities. Correspondence of simulated XRD patterns with synchrotron powder diffraction experiments is achieved on the conditions that beside of 90o rotations of brownmillerite-like domains inside perovskite-like matrix each domain contains areas with perpendicularly oriented tetrahedral chains. Influence of such parameters as stoichiometry, average domain size, orthorhombic distortion degree on the XRD patterns is considered.

Class-1 polypeptide chain release factors (RFs) trigger hydrolysis of peptidyl-tRNA at the ribosomal peptidyl transferase center mediated by one of the three termination codons. In eukaryotes, apart from catalyzing the translation termination reaction, eRF1 binds to and activates another factor, eRF3, which is a ribosome-dependent and eRF1-dependent GTPase. Because peptidyl-tRNA hydrolysis and GTP hydrolysis could be uncoupled in vitro, we suggest that the two main functions of eRF1 are associated with different domains of the eRF1 protein. We show here by deletion analysis that human eRF1 is composed of two physically separated and functionally distinct domains. The “core” domain is fully competent in ribosome binding and termination-codon-dependent peptidyl-tRNA hydrolysis, and encompasses the N-terminal and middle parts of the polypeptide chain. The C-terminal one-third of eRF1 binds to eRF3 in vivo in the absence of the core domain, but both domains are required to activate eRF3 GTPase in the ribosome. The calculated isoelectric points of the core and C domains are 9.74 and 4.23, respectively. This highly uneven charge distribution between the two domains implies that electrostatic interdomain interaction may affect the eRF1 binding to the ribosome and eRF3, its activity in the termination reaction and activation of eRF3 GTPase. The positively charged core of eRF1 may interact with negatively charged rRNA and peptidyl-tRNA phosphate backbones at the ribosomal eRF1 binding site and exhibit RNA-binding ability. The structural and functional dissimilarity of the core and eRF3-binding domains implies that evolutionarily eRF1 originated as a product of gene fusion.