Table of contents

A magnetic fluid (MF) is a liquid dispersion of magnetic nanoparticles coated by surfactants for stabilization. The MF research reviewed in this paper is primarily aimed at investigating the atomic and magnetic structure of MF particles and the way they interact under various conditions by means of small-angle neutron scattering (SANS). The presence of a liquid carrier in the structure and the magnetic properties of MFs, which are very close to those of an ideal superparamagnetic system, allow the effective use of the major neutron scattering features: the strong effect of hydrogen–deuterium isotopic substitution and magnetic scattering. An extension of the contrast variation technique to the structure research on polydisperse and superparamagnetic systems is proposed. The cases of noninteracting and interacting particles, the latter with cluster formation taken into account, are considered for non-magnetized and magnetized MFs. The polarized neutron scattering analysis of the structure of magnetized MFs is illustrated by examples. Topical problems in further developing the method to study multiparameter systems are identified.

This review discusses the state of the art in two related research areas: the surfaces of niobium and of its related group IV–VI transition metals, and surface (primarily oxide) nanostructures that form on niobium (and group IV–VI d-metals) due to gas adsorption or impurity diffusion from the bulk. Experimental (X-ray photoelectron spectroscopy, photoelectron diffraction, scanning tunneling microscopy) and theoretical (ab initio simulation) results on d-metal surfaces are summarized and reviewed.

It is shown that the presence of nano-sized and nano-structured erosion products not only affects the operation of thermonuclear devices but also, to a large extent, determines the safety and economy of future thermonuclear reactors. The formation mechanisms and the characteristics and properties of deposited films and nano-sized dust that form in tokamaks are reviewed.

A review of various systems for automated calculation of tree-level and loop Feynman diagrams, Monte Carlo integration over multidimensional phase space, and event generation for modern and future colliders (LHC and ILC) is presented. The CompHEP system possibilities are considered in greater detail.

The present paper considers melting criteria for a plasma crystal discovered in dust plasma in 1994. Separate discussions are devoted to three-dimensional (3D) and two-dimensional (2D) systems. In the 3D case, melting criteria are derived based on the properties of local order in a system of microparticles. The order parameters are constructed from the cumulative distributions of the microparticle probability distributions as functions of various rotational invariants. The melting criteria proposed are constructed using static information on microparticle positions: a few snapshots of the system that allow for the determination of particle coordinates are enough to determine the phase state of the system. It is shown that criteria obtained in this way describe well the melting and premelting of 3D complex plasmas. In 2D systems, a system of microparticles interacting via a screened Coulomb (i.e., Debye–Hückel or Yukawa) potential is considered as an example, using molecular dynamics simulations. A number of new order parameters characterizing the melting of 2D complex plasmas are proposed. The order parameters and melting criteria proposed for 2D and 3D complex plasmas can be applied to other systems as well.

Three possible settings are considered for the question of two interacting charged conducting balls: (1) both balls are kept at constant and equal potentials; (2) one ball is charged and isolated, the other is kept at a constant potential with the same sign as the first, and (3) both balls are like charged and isolated. It is shown that fundamentally different problems generally arise here: whereas in the first case the balls always repel, in the second and third cases fairly wide ranges of radius and charge ratios can always be found in which the balls attract each other at close distances. These ranges are identified in the paper. The results are presented of experiments that demonstrate both the repulsion and attraction of like-charged balls. Theory and experiment show satisfactory agreement, both qualitatively and quantitatively.