Magnetosonic Waves in a Two-Dimensional Electron Fermi Liquid

Semiconductors - The properties of highly viscous fluids at high frequencies become similar to those of amorphous solids. In particular, the propagation of not only longitudinal acoustic waves...     

2D Atomic-Topological Model of the Dissolution Kinetics of a Metallic Crystal: Typical Atomic Relief Positions and Fragments

The atomic-topological kinetics problem of the self-consistency between the dissolution kinetics and the atomic relief of the dissolving boundary is solved for an imaginary two-dimensional crystal in two ways: (i) in terms of the model of atomic positions determined by the number of the nearest neighbors and (ii) in terms of the typical atomic relief structures (steps, kinks, etc.). To a sufficient accuracy, the results provided by these two models coincide. The approaches developed are aimed at solving the problem of the dissolution of an actual three-dimensional crystal.__________Translated from Zashchita Metallov, Vol. 41, No. 3, 2005, pp. 244–257.Original Russian Text Copyright © 2005 by G. Alekseev, Yu. Alekseev, Bityurin.     

Structure of reciprocal lattice sites of a single-crystal Ni-based superalloy

Volume fractions of the ?? phase are calculated in the form of various geometrical figures depending on the ratio of the volume fraction of the ?? and ?á? phases. The ?? phase in the form of plates prevails at a 70% content of the ?á? phase, which is the most characteristic of the VZhM4 alloy after the complete heat treatment. The qualitative analysis is carried out for the arrangement of satellites in the reciprocal space of the VZhM4 single-crystal Ni-based superalloy. The lattice of the reciprocal space with the satellites caused by the stress state of ?? phase interlayers is constructed in the form of various geometrical figures. The set of experimental sections of the 3D structure of (222), (313), and (202) reciprocal lattice sites is obtained.     

Effects of mutations in the calcium-binding sites of recoverin on its calcium affinity: evidence for successive filling of the calcium binding sites

A molecule of the photoreceptor Ca²⁺-binding protein recoverincontains four potential EF-hand Ca²⁺-binding sites, of whichonly two, the second and the third, are capable of binding calciumions. We have studied the effects of substitutions in the second,third and fourth EF-hand sites of recoverin on its Ca²⁺-bindingproperties and some other characteristics, using intrinsic fluorescence,circular dichroism spectroscopy and differential scanning microcalorimetry.The interaction of the two operating binding sites of wild-typerecoverin with calcium increases the protein's thermal stability,but makes the environment around the tryptophan residues moreflexible. The amino acid substitution in the EF-hand 3 (E121Q)totally abolishes the high calcium affinity of recoverin, whilethe mutation in the EF-hand 2 (E85Q) causes only a moderatedecrease in calcium binding. Based on this evidence, we suggestthat the binding of calcium ions to recoverin is a sequentialprocess with the EF-hand 3 being filled first. Estimation ofCa²⁺-binding constants according to the sequential binding schemegave the values 3.7 x 10⁶ and 3.1 x 10⁵ M^–1 for thirdand second EF-hands, respectively. The substitutions in theEF-hand 2 or 3 (or in both the sites simultaneously) do notdisturb significantly either tertiary or secondary structureof the apo-protein. Amino acid substitutions, which have beendesigned to restore the calcium affinity of the EF-hand 4 (G160D,K161E, K162N, D165G and K166Q), increase the calcium capacityand affinity of recoverin but also perturb the protein structureand decrease the thermostability of its apo-form.     

Strength improvement of iPP/MWCNT nanocomposites

The mechanisms of microhardness increase in thermoplastic polypropylene/multi‐walled carbon nanotubes (MWCNT) nanocomposites during electron irradiation (E_e = 1.8 MeV) with different absorption doses are investigated. The crystal structure of the nanocomposites, Raman scattering, and microhardness in a MWCNT concentration range between 0.1 and 5.0 wt% is studied in detail. During irradiation, changes in the degree of crystallinity of the polymer matrix, lattice parameters of the topologically ordered phase, Raman scattering, and microhardness show a complex conjugation process between the composite components. Their interaction is accomplished as the result of the formation of new bonds, which appeared with the radiation damages. Furthermore, the crosslinking of the internal MWCNT layers also contributes to an increase in the strength properties of the polymer nanocomposites. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Development of Heat Treatment Modes for Novel Structural Sparingly Alloyed High-Strength Steel for Arctic and Far North Applications

Metal Science and Heat Treatment - The structure and mechanical properties of novel structural high-strength cold-resistant steel 20G2SMRA are studied after quenching and tempering at different...