Carbonized fibers based on polyvinyl alcohol

On the basis on polyvinyl alcohol (PVA), carbonized fibers were produced in the form of a complex technical thread with tensile strength above 200 MPa and specific electrical conductivity of at least 0.5 S/cm. Using thermogravimetric and differential thermal analysis, Raman scattering, and wide-angle X-ray diffraction, structures of these fibers were characterized. The structural parameters of carbonized PVA fibers are close to the parameters of carbonized coal tar pitch obtained by heat treatment at 1000°C. The structure and properties of carbonized fibers modified with potassium bisulfate were also studied.     

Influence of monopole pairing on the energies of single-nucleon states in the problem of superconducting pairing correlations

A correlation function, the chemical potential, coefficients in a special Bogolyubov transformation, and single-quasiparticle energies were calculatedwith allowance for the effect of the monopole-pairing potential on the energies of single-particle nucleon states in the mean nuclear field.     

Regularities of thermolysis for the Fe(II), Co(II), and Ni(II) salts of maleic and ortho-phthalic acids with the formation of metal/polymer composites

Russian Journal of Coordination Chemistry - Regularities of the thermolysis of acidic salts of unsaturated (maleic) [M(H2O)4(C4H3O4)2] and aromatic (ortho-phthalic) [M(H2O)6](C8H5O4)2 (M = Fe(II),...     

Effect of uniform magnetic and electric fields on microstructure and substructure characteristics of combustion products of aluminum nanopowder in air

We have analyzed the effect of constant electric and magnetic fields on the micro- and substructure characteristics of the combustion products of aluminum nanopowder in air. It has been found that the combustion of aluminum nanopowder in a magnetic field leads to the formation of single crystals of the hexagonal habitus, while the combustion in an electric field results in the formation of faceted crystallites with layered morphology. The fields noticeably affect the crystal lattice parameters of aluminum oxide and nitride (reduce the coherent scattering regions in aluminum nitride and increase such regions in aluminum γ-oxide). At the same time, the displacement of atoms relative to the equilibrium position becomes noticeably smaller for all crystal phases under the action of the fields (except for aluminum nitride in a magnetic field). These results have been explained by the orienting and stabilizing actions of the fields on the combustion products of aluminum nanopowder in air.     

The numerical duplication of a numerical semigroup

In this paper we present and study the numerical duplication of a numerical semigroup, a construction that, starting with a numerical semigroup S and a semigroup ideal E?S, produces a new numerical semigroup, denoted by S? ^b E (where b is any odd integer belonging to S), such that S=(S? ^b E)/2. In particular, we characterize the ideals E such that S? ^b E is almost symmetric and we determine its type.     

Nanofibers prepared by electrospinning from solutions of biobased polyamide 4

A successful preparation of polyamide 4 nanofibers via electrostatic spinning with diameters close to 100 nm is described. Polyamide 4 was prepared by the anionic ring‐opening polymerization of 2‐pyrrolidone and characterized. The effect of the system parameters (i.e., molar mass of the polymer, the solvent system) and the process parameters (i.e., the electrode‐to‐collector distance) during the electrostatic spinning have been studied. The morphology of the polyamide 4 fiber layers is given except molar mass of the polymer and the concentration of its solution primarily by the conformation of polyamide chains due to polyelectrolyte effect which was confirmed by viscosity measurements. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2203–2210     

Growth and optical properties of filamentary GaN nanocrystals grown on a hybrid SiC/Si(111) substrate by molecular beam epitaxy

The potential to grow filamentary GaN nanocrystals by molecular beam epitaxy on a silicon substrate with a nanosized buffer layer of silicon carbide has been demonstrated. Morphological and optical properties of the obtained system have been studied. It has been shown that the intensity of the photoluminescence spectrum peak of such structures is higher than that of the best filamentary GaN nanocrystals without the buffer silicon carbide layer by a factor of more than two.