On the mechanism of rendering visible dislocations on the surface of iron crystals by anodic dissolving

The paper contains further results of studying dislocations rendered visible by anodic dissolving on the surface of single crystals of alpha-iron. The influence of the crystallographic orientation of the surface is investigated, the effect of carbon is confirmed and the anodic process is studied. The mechanism of dissolving of the crystal is given and a new more suitable method of rendering dislocations visible is derived.

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The author thanks F. Kroupa and J. Hejduk for critical remarks and discussion.     

The sub-structure of crystals of silicon-iron alloy

After electrolytic polishing and etching a network of boundaries between mosaic blocks was observed on the surface of single crystals of silicon-iron alloy prepared from the melt. Some of the boundaries are formed by a number of distinguishable pits, also found singly outside the boundary. An explanation is given on the basis of the conception that the pits are etched points of intersection of edge dislocations with the surface of the crystals.     

Statistical description of the system electrons on the liquid helium surface

System of electrons on the liquid helium surface is considered. General methods for obtaining free energy functional for the systems in mean field approximation are developed. These methods applied for treating systems with particles arranged in a lattice. Thus obtained functional of free energy is analyzed. The localization distance for electron and conditions for existing square or triangular lattices as well as phase transition between them are obtained.     

Redox Properties of Novel Dinuclear Ni(II) Bis - Tetraazamacrocyclic Complex

Abstract

Dinuclear Ni(II) bis-tetraazamacrocyclic complex 1 with conjugated double bonds at deprotonated β-diimine linking group was characterized by ¹H NMR and cyclic voltammetry. Electrochemical studies indicated high stability of the mixed-valence (Ni^II- Ni^III) and (Ni^II- Ni^I) species, respectively. The main factor contributing to the stabilization of the mixed-valence states is the electronic delocalization through the system of the conjugated double bonds at the deprotonated β-diimine linking group. Complex 1 is the first example of dinuclear Ni(II) tetraazamacro-cyclic complex exhibiting two one-electron oxidation and two one electron reduction steps.     

Investigation of protein FTT1103 electroactivity using carbon and mercury electrodes. Surface-inhibition approach for disulfide oxidoreductases using silver amalgam powder

Recently, it was shown that electrochemical methods can be used for analysis of poorly water-soluble proteins and for study of their structural changes and intermolecular (protein–ligand) interactions. In this study, we focused on complex electrochemical investigation of recombinant protein FTT1103, a disulfide oxidoreductase with structural similarity to well described DsbA proteins. This thioredoxin-like periplasmic lipoprotein plays an important role in virulence of bacteria Francisella tularensis. For electrochemical analyses, adsorptive transfer (ex situ) square-wave voltammetry with pyrolytic graphite electrode, and alternating-current voltammetry and constant-current chronopotentiometric stripping analysis with mercury electrodes, including silver solid amalgam electrode (AgSAE) were used. AgSAE was used in poorly water-soluble protein analysis for the first time. In addition to basic redox, electrocatalytic and adsorption/desorption characterization of FTT1103, electrochemical methods were also used for sensitive determination of the protein at nanomolar level and study of its interaction with surface of AgSA microparticles. Proposed electrochemical protocol and AgSA surface-inhibition approach presented here could be used in future for biochemical studies focused on proteins associated with membranes as well as on those with disulfide oxidoreductase activity.     

Layered Double Hydroxides as the Unique Product of Target Ionic Construction for Energy,Chemical, Foods,Cosmetics, Medicine and Ecology Applications

Layered Double Hydroxide (LDH) is an α-modification of the M-host (M²⁺) hydroxide, in which some part of the M-host cations is replaced by M-guest cations (M³⁺ or M⁴⁺). The emerging excess positive charge is compensated by the intercalation of anions into the interlayer space, which also contains water molecules. LDHs exhibit anion exchange properties. Targeted ionic design of LDHs via combining three components (M-host, M-guest cations, intercalated anions) allows the creation of a very wide range of highly efficient electrochemical, electrocatalytic, electrochromic substances, catalysts, ion exchangers, sorbents, color pigments, pharmacological drugs, food, and cosmetic additives. In this review, the structure and areas of application of LDHs are considered from the perspective of the targeted ionic design of a substance for a specific application.     

Side-chain crystallinity. II. Heats of fusion and melting transitions on selected copolymers incorporating n-octadecyl acrylate or vinyl stearate

The heats of fusion and the melting transitions of the crystallinity present in the side chains were determined for selected copolymers incorporating n-octadecyl acrylate or vinyl stearate. A major purpose of this investigation was to ascertain the effect of interrupting the long ordered 18-carbon side chains by randomly interspersed amorphous side chains of various lengths. For this purpose the lower acrylate homologs (C₁ through C₈ and including oleyl, C₈) were copolymerized over the composition range with n-octadecyl acrylate. It was found that simple dilution of the crystalline component (from comonomer b) by the amorphous component (from comonomer a) governed the decline in the heats of fusion and the fraction of crystallinity present. High crystallization rates were encountered because equilibrium crystallinity was nearly achieved for most of the copolymers. Melting point depression was less than theory in copolymers having short amorphous comonomer side chain lengths, but approached the theoretical depression as these side chains became very long. Thus the outer methylene sequences (the crystalline sequences) of the fatty co-units could bridge the smaller amorphous a units, giving rise to larger crystal sizes than theory specified. Main-chain stiffness, when present in the melt, had a small effect on the distribution of crystallite sizes but exhibited a much larger influence in preventing the attainment of equilibrium crystallinity, especially at high amorphous comonomer compositions. However, crystallinity was still high compared with that of copolymers described in the literature crystallizing through their main-chain units. When long blocks of crystalline segments were present (as in compositionally heterogeneous vinyl stearate copolymers), melting point depression was small and followed the theoretical probability sequence function.