Deformation of a surface layer and coating application using a flexible tool

The microstructure and properties of the functional coatings formed by impact friction processing of product surfaces with a flexible tool are studied. It is established that the processing produces a hard nanostructured surface layer with fragments up to 0.13 µm in size, as it is achieved by severe plastic deformation.     

A study of reinforced refractory concretes

Results of a laboratory study of the properties of corundum concrete with metallic fibers of five compositions are presented. It is shown that some of the fibers affect favorably the strength and heat resistance of the concrete. Industrial tests of parts made of the suggested reinforced concrete have proved these conclusions.Translated from Ogneupory i Tekhnicheskaya Keramika, No. 11, pp. 22–24, November, 1996.     

Effect of sulfuric acid treatment on the physicomechanical properties of polyphenyleneoxadiazole fibres

Conclusions By treatment of undried polyphenyleneoxadiazole yarns with concentrated sulfuric acid under isometric conditions, it is possible to raise their strength by 20–30% and their elongation at break 40–50%.The improvement in physicomechanical properties of the yarns which have been treated with acid is caused by a reduction in internal stresses, an improvement in the interlayer packing of the macromolecules fragments, and an increase in the degree of orientation of the macromolecules.Translated from Khimicheskie Volokna, No. 6, pp. 33–35, November–December, 1985.     

Telomere Length in Metaphase Chromosomes of Human Triploid Zygotes

The human lifespan is strongly influenced by telomere length (TL) which is defined in a zygote—when two highly specialised haploid cells form a new diploid organism. Although TL is a variable parameter, it fluctuates in a limited range. We aimed to establish the determining factors of TL in chromosomes of maternal and paternal origin in human triploid zygotes. Using Q-FISH, we examined TL in the metaphase chromosomes of 28 human triploid zygotes obtained from 22 couples. The chromosomes’ parental origin was identified immunocytochemically through weak DNA methylation and strong hydroxymethylation in the sperm-derived (paternal) chromosomes versus strong DNA methylation and weak hydroxymethylation in the oocyte-derived (maternal) ones. In 24 zygotes, one maternal and two paternal chromosome sets were identified, while the four remaining zygotes contained one paternal and two maternal sets. For each zygote, we compared mean relative TLs between parental chromosomes, identifying a significant difference in favour of the paternal chromosomes, which attests to a certain “imprinting” of these regions. Mean relative TLs in paternal or maternal chromosomes did not correlate with the respective parent’s age. Similarly, no correlation was observed between the mean relative TL and sperm quality parameters: concentration, progressive motility and normal morphology. Based on the comparison of TLs in chromosomes inherited from a single individual’s gametes with those in chromosomes inherited from different individuals’ gametes, we compared intraindividual (intercellular) and interindividual variability, obtaining significance in favour of the latter and thus validating the role of heredity in determining TL in zygotes. A comparison of the interchromatid TL differences across the chromosomes from sets of different parental origin with those from PHA-stimulated lymphocytes showed an absence of a significant difference between the maternal and paternal sets but a significant excess over the lymphocytes. Therefore, interchromatid TL differences are more pronounced in zygotes than in lymphocytes. To summarise, TL in human zygotes is determined both by heredity and parental origin; the input of other factors is possible within the individual’s reaction norm.     

Properties of silicon-containing carbon fiber materials prepared using cellulose

Silicon-containing carbon fiber sorbents, which exhibited sufficiently high sorption activity and increased stability to the action of oxygen at high temperatures, as compared with that of an analogous material based on individual cellulose, were prepared by the carbonization and the subsequent activation of cellulose compositions with polycarbosilane.     

Antioxidant properties of humic acids from brown coal

It was demonstrated by a gas-volumetric method that humic acids from brown coal exhibit pronounced antioxidant properties, being the effective inhibitors of the model reactions of initiated radicalchain oxidation of hydrocarbons (cumene and ethylbenzene). This makes it possible to recommend humic acids for use as effective antioxidants for technical purposes and as promising biologically active natural antioxidants for the development of new classes of pharmaceuticals for medicine.     

Phase coexistence in Bi1−x Pr x FeO3 ceramics

Bi_1?x Pr _x FeO₃ ceramics across the rhombohedral–orthorhombic phase boundary have been studied by X-ray diffraction, transmission electron microscopy, and differential scanning calorimetry. The structural phase transitions in Bi_1?x Pr _x FeO₃ driven by doping concentration and temperature are significantly different from those in BiFeO₃ compounds doped with other rare-earth elements. The features of the structural transformations have been discussed based on the specific character of the chemical bonds associated with praseodymium ions. The detailed study of the crystal structure evolution clarified the ranges of both single-phase and phase coexistence regions at different temperatures and dopant concentrations. For x = 0.125, compound extraordinary three-phase coexistence state has been observed in a narrow temperature range at about 400 °C. The results explicate driving forces of the structural transitions and elucidate the origin of the remarkable physical properties of BiFeO₃-based compounds near the morphotropic phase boundary.     

Sensitized anti-stokes luminescence centers in AgCl crystals

In the AgCl microcrystals with adsorbed methylene blue dye molecules, sensitized anti-Stokes luminescence centers formed as a result of a photostimulated low-temperature (77 K) process are observed. The emission is recorded on excitation of the samples by radiation with the flux density 10¹⁴?10¹⁵ photon cm^?2 s^?1 in the spectral range 620–750 nm corresponding to optical absorption in the adsorbed dye molecules and adsorbed Ag₁, Ag₂, and Ag₃ clusters. It is shown that the anti-Stokes luminescence centers formed by photo-stimulation present (adsorbed dye molecule)—(silver subnanocluster) hybrid nanostructures, in which the bonding between the components is weak but sufficient to provide the possibility for two-photon interband transitions that occur due to transfer of the electron’s excitation energy from the dye molecule to the silver cluster with subsequent photoionization of the cluster.