Volume 473, Nº 2 (2017)

A mechanism is suggested for pore formation in n-type Si through the stage of nucleation in the most probable places.

A new strategy for the synthesis of fluorene-containing polyphenols of porphyrin series by the Suzuki–Miyaura reaction of hexabromoporphyrin and monoboryl derivative of substituted fluorene has been proposed. Several sequential chemical transformations of the prepared porphyrin allowed preparation of polyphenol derivative of the noted compound. Similar polyphenol has been used as a basis for the design of positive photoresists for nanolithography with 13.5-nm exposing radiation, which can produce topological structures with resolution 22–16 nm.

Conditions of tritium introduction into 5-oxo-Pro-Arg-Pro have been developed. Labelled 5-oxo-Pro-Arg-Pro has been obtained in 75% yield and molar radioactivity of 60 Ci/mmol. Tritium distribution over amino acid residues in the peptide has been determined. 5-Oxo-Pro : Arg : Pro ratio in the labelled peptide has been found to be 1 : 5.2 : 2.8. Nonterminal amino acid has been found to contain the major portion of tritium, about 35 Ci/mmol; i.e., arginine includes more than half of the label. Such a feature can be explained by the effect of readily protonated guanidine group of arginine. The influence of charged guanidine group of arginine seems to increase the shift of electron density in the neighboring C–H bonds of arginine and proton mobility, thus increasing protium–tritium exchange at these carbon atoms.

The structures and phase compositions of a series of Co–9 at % Al–x at % W alloys (where x = 4.6, 6.8, 8.5, 10.0, 12.6) have been studied. All of them are dominated by the structure γ + γ′, with the content of other phases (the μ phase and the phase D0₁₉ based on Co₃W) being insignificant. With increasing tungsten content of the alloy (to 10 at % W), the volume fraction of the γ′ phase increases, and so does its degree of long-range order. The alloy that is optimal in structure and mechanical properties has the composition Co–8.2 at % Al–8.5 at % W. The dissolution range of the γ′ phase was determined as 920–1054°C. Young’s moduli of cobalt alloys exceed E of commercial nickel-based superalloys. The samples of the studied alloys are in the ferromagnetic state with a Curie temperature of 870°C. With increasing tungsten content of the alloy, its saturation magnetization decreases and the coercive force increases. The coercive force is minimal in an as-cast sample and increases as it is subjected to deformation or heat treatment.

A study was made of the role of high-temperature shear deformation in the processes of combustion and structuring of titanium carbide, which lead to changes in the grain size and morphology and in the quality of the end product. It was shown that, by applying shear loads to the as yet unformed material, the structure and morphology of the obtained powder can be affected. Shear deformation during self-propagating high-temperature synthesis results in an almost 100% yield of a powder with a particle size of less than 400 μm.