Electron screening in low energy scattering of muonic hydrogen on hydrogen atoms

Electron screening corrections to the cross sections for low energy scattering of muonic hydrogen on hydrogen atoms are calculated. It is shown that the presence of the electron influences considerably the elastic cross sections at collision energies below 1 eV. This influence is relatively small for the spin-flip and isotopic exchange processes.     

Quasiresonance charge exchange of hydrogen isotopes mesic atoms in excited states

Processes of charge exchange of hydrogen isotopes mesic atoms in excited states at low collision energies 10^?2?E?1 eV are studied. The cross sections calculated depend on energy like ～E ^?1 and are of an order of the atomic cross sections (～10^?16 cm²). It is shown that the high rates (～10¹² s^?1) of charge exchange and thermalization of mesic atoms in excited states at the liquid hydrogen density are comparable with the rates of cascade transitions in mesic atoms.     

Analysis of the structure of block copolymer films by atomic force microscopy

The structure of thin films of the polysterene-polymethylacrylate-polysterene triblock copolymer was studied. Universal algorithms to analyze atomic-force-microscopy images of thin block-copolymer films were developed.     

A model estimate of the fine structure constant

A model that provides the lower bound estimate of the fine structure constant which is consistent with the experimental value is considered.     

Concentration Front Propagation and Adsorption of Impurities during Filtration of a Nanofluid through a Porous Medium

Journal of Applied Mechanics and Technical Physics - Direct numerical simulation of the process of filtration of nanofluids through a porous medium has been performed. The phenomenon of pore...     

Investigation of the spin-glass state in γ-Fe-Ni-Mn alloys

The composition region where there are no long-range ferro- and antiferromagnetic order has been determined in γ-Fe-Ni-Mn alloys. In these alloys strong small-angle magnetic neutron scattering has been obtained. The intensity has an unusual temperature dependence which is discussed in the framework of the critical neutron scattering thermodynamic theory. The ground state of these alloys is identified with the spin-glass state in which there are also regions of both short-range ferro- and antiferromagnetic order.     

Local moment model for the Invar effect

It has been shown by small-angle neutron scattering that the magnetic structure of Invar alloys in the ground state is characterized by the occurrence of static magnetic fluctuations on the scale of 10–12 Å. Centres of such fluctuations are iron atoms surrounded by the same sort of atoms in the nearest coordination sphere. These fluctuations are due to antiferromagnetic iron pair interactions. The magnetic part of thermal expansion coefficient of Fe-Ni alloys is evaluated within the framework of the molecular field approximation. The Invar effect is brought about by a mixed exchange interaction and by a strong dependence of the exchange integral J_FeFe on the interatomic distance.     

Cluster-Type Structure of Amorphous Smooth Hydrocarbon CD<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> Films (<Emphasis Type="Italic">x</Emphasis> ~ 0.5) from T-10 Tokamak

Structure of smooth hydrocarbon CD _x films with a high deuterium ratio x ~ 0.5 redeposited from T-10 tokamak D-plasma discharges (NRC Kurchatov Institute, Moscow) has been studied. For the first time, small and wide angle X-ray scattering technique using synchrotron radiation and neutron diffraction have been employed. A fractal structure of CD _x films is found to consist of mass-fractals with rough border, surface fractals (with rough surface), plane scatterers and linear chains forming a branched and highly cross-linked 3D carbon network. The found fractals, including sp² clusters, are of typical size ~1.60 nm. They include a C₁₃ fragment consisting of three interconnected aromatic rings forming a minimal fractal sp² aggregate 9 × C₁₃. These graphene-like sp² clusters are interconnected and form a 3D lattice which can be alternatively interpreted as a highly defective graphene layer with a large concentration of vacancies. The unsaturated chemical bonds are filled with D, H atoms, linear sp² C=C, C=O, and sp³ structural elements like C-C, C-H(D), C-D_2,3, C-O, O-H, COOH, C _x D(H) _y found earlier from the infrared spectra of CD _x films, which are binding linear elements of a carbon network. The amorphous structure of CD _x films has been confirmed by the results of earlier fractal structure modeling, as well as by researches with X-ray photoelectron spectroscopy which allow finding a definite similarity with the electron structure of their model analogues — polymeric a-C:H and a-C:D films with a disordered carbon network consisting of atoms in sp³ + sp² states.     

On the connectivity properties of the complementary set in fractal percolation models

We study the connectivity properties of the complementary set in Poisson multiscale percolation model and in Mandelbrot's percolation model in arbitrary dimension. By using a result about majorizing dependent random fields by Bernoulli fields, we prove that if the selection parameter is less than certain critical value, then, by choosing the scaling parameter large enough, we can assure that there is no percolation in the complementary set.