Modulation of the internal structure and surface properties of natural and synthetic polymer matrices by graphene oxide doping

Controlling the surface properties and structure of thin nanosized coatings is of primary importance in diverse engineering and medical applications. Here we report on how the nanostructure, growth mechanism, thickness, roughness, and hydrophilicity of nanocomposites composed of weak natural or strong synthetic polyelectrolytes (PE) can be tailored by graphene oxide (GO) doping. GO reverses the build‐up mechanism affecting the internal structure and the hydrophilicity in a way depending on the type of the PE‐matrix. The extent of GO‐adsorption and its impact on the surface morphology was found to be independent on the type of the underlying PE‐matrix. The nanostructure of the hybrid films is not significantly altered when a single surface‐exposed GO‐layer is deposited, while increasing the number of embedded GO‐layers leads to pronounced surface heterogeneity. These results are expected to have valuable impact on the construction strategies of coatings with tunable surface properties.     

Mössbauer total external reflection: Composition of surface layers

An ambiguity of Mössbauer spectra measured under total external reflection conditions due to the increase of the number of parameters which should be determined can be compensated by measuring a series of experimental spectra. The interpretation of all experimental data must be done by means of numerical modeling (or fitting). The method enables us to study phase transformations within a layer of about 10 nm thickness.     

Quasiisotropic and uniform approximations of geometrical optics

Kaliningrad State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 35, No. 1, pp. 50–60, January, 1992.     

Secondary radiation emission at Mössbauer total external reflection

The effects of energy dependence of secondary radiation emission (SRE) followed by nuclear resonant and nonresonant photo-absorption at Mössbauer total external reflection (MTER) have been considered theoretically and checked experimentally. Numerical interpretation of a set of MTER and CEM spectra at different grazing angles has given the depth profiles of electronic density, photoabsorption coefficient and hyperfine interaction variations in 50 nm slightly oxidized⁵⁷Fe film. Empirical functions of photo- and conversion electron yield are also determined. They appeared to be nonsimilar and nonmonotone. The energy dependencies of SRE are recalculated for time domain Mössbauer spectroscopy of synchrotron radiation (SR). The coherent nature of the TER effect reveals itself in the existence of delayed intensity of nonresonant SRE. The relation of nonresonant and resonant SRE, their energy, time and angular spectra strongly depend upon the depth of their creation, which opens a way for depth selective measurements as in the X-ray standing waves method.     

Nuclear Resonant Reflectivity Investigations of a Thin Magnetic 57Fe Layer Adjacent to a Superconducting V Layer

Hyperfine Interactions - With nuclear resonant scattering of synchrotron radiation we have investigated the magnetic hyperfine fields of a thin (～2 nm) 57Fe layer below and above the...     

Local particle densities and global multiplicities in central heavy ion interactions at 3.7, 14.6, 60 and 200A GeV

The energy and centrality dependence of local particle pseudorapidity densities as well as validity of various parametrizations of the distributions are examined. The dispersion, , of the rapidity density distribution of produced particles varies slowly with centrality and is 0.80, 0.98, 1.21 and 1.41 for central interactions at 3.7, 14.6, 60 and 200A GeV incident energy, respectively, is found to be independent of the size of the interacting system at fixed energy. A novel way of representing the window dependence of the multiplicity as normalized variance versus inverse average multiplicity is outlined.     

28Si(32S) fragmentation at 3.7 A, 14.6 A and 200 A GeV

The fragmentation topology of²⁸Si at 3.7A GeV and 14.6A GeV and³²S at 200A GeV in reactions with emulsion nuclei is presented. The fragmentation cross sections are very similar at all three energies. A statistical percolation model can qualitatively describe the data forZ 6. The He production is underestimated and the 3 Z 5 fragments overestimated by this model.     

Synthesis and spectral-luminescence properties of 4(5)-(1,5-diaryl-Δ2-pyrazolin-3-yl)-1,8-naphthoylene-1′,2′-benzimidazole with fluorine- containing substituents

A number of 4(5)-(1,5-diaryl-²-pyrazolin-3-yl)-1,8-naphthoylene-l',2'-benzimidazoles with fluorine-containing substituents in the benzene ring of the naphthoylenebenzimidazole fragment or the N-aromatic grouping of the pyrazoline ring were synthesized by the reaction of 4(5) -acetyl-1,8-naphthoylene-1,2-benzimidazole or its substituted derivatives with benzaldehyde and subsequent condensation of the resulting cinnamoylnaphthoylenebenzimidazoles with phenylhydrazine or substituted phenylhydrazines. The compounds obtained fluoresce intensively in liquid organic solvents and in polymeric matrices and have increased photostability.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1245–1247, September, 1982.