Liquid plasma crystal: Coulomb crystallization of cylindrical macroscopic grains in a gas-discharge plasma

Ordered structures formed of 300-μm-long cylindrical nylon grains with diameters of 15 and 7.5 μm are obtained. In contrast to conventional spherical monodisperse grains, which, under certain conditions, form the plasma-dust Coulomb crystal, the cylindrical grains in the plasma acquire a charge of ～7×10⁵ electrons and form a structure similar to a liquid crystal. The parameter characterizing the nonideality of the dusty component of the plasma attains 10⁶. Grains are suspended in the striation in the horizontal plane and line up in parallel with each other.     

Investigation of low-frequency normal waves in a Biot layer surrounded by an elastic medium

The porous Biot layer surrounded by two elastic half-plates is considered. For this medium, two dispersion equations are established. These dispersion equations correspond to symmetric and antisymmetric parts of the medium. The investigation of these equations is conducted in the region of low frequencies. The imaginary roots of these equations in this region determine low-frequency normal waves. Bibliography: 6 titles.     

On the problem of monitoring hydrocarbon reservoirs during production

The problem of monitoring the position of the boundary of a hydrocarbon collector as a source approaches, is discussed. Day surface seismograms are analyzed. Specific properties of the anomalous S* wave are used. The case of a porous medium inside a reservoir is also considered. Bibliography: 24 titles.     

Relationships of graft polymerization of vinyl monomers onto cellulose. Reaction kinetics and polymer structure

Graft polymerization of acrylamide and sulfuric salt of 2-methyl-5 vinylpyridine onto cellulose using CO(III) salts was studied. It was shown that graft polymerisation of water-soluble polymers can be described by general relationships of radical reaction. The relation between elementary reaction constants of the formation and termination of active centers in cellulose, as well as relation between constants of the propagation, transfer and termination of chains were determined for different cellulose materials and monomers. The translational diffusion, sedimentation, viscosity, and flow birefringence of copolymers have been investigated in different solvents. Experimental data showed that the copolymers obtained are graft copolymers with two to five grafted chains onto macromolecules. The minimum distance between the branch points is 100 ± 20 glucoside units. The peculiarity of these copolymers is relatively low polydispersity. The conformation of macromolecules of such copolymers in solution depends on the compatibility of the copolymer components and the thermodynamic properties of the solvent.     

Self-action of short pulses in nonhomogeneous graded-index light guides

The weak nonlinear process of propagation of short pulses in graded-index light guides that are weakly inhomogeneous in the longitudinal direction and slightly bent is investigated by means of a consistent asymptotic method. The process as a whole is proved to be three-scale in respect to a small parameter related to the magnitude of nonlinearity. The phase of the most rapid process and transverse distribution of the wave field are expressed explicitly in terms of a certain Sturm-Liouville problem. For a pulse envelope the nonlinear Schrödinger equation is derived, its coefficients depending on the longitudinal coordinate. The existence of a guaranteed interval of conservation of concentration of the pulse envelope is ascertained. For a class of very smooth inhomogeneities formulae are obtained describing the variation of the amplitude and width of the pulse during propagation.     

On the privacy-preserving cascade method for correcting errors in primary keys in quantum cryptography

A general method is proposed for privacy protection upon correction of errors in primary keys in quantum cryptography through an open communication channel. By the example of the cascade procedure for correcting errors, a method is described for removing information sent through an open communication channel when cleaning a key. The critical percentage is found for the quantum cryptography protocol BB84 to which the cascade error correction method with deletion guarantees the security of the final key. The method proposed for removing information sent through the open communication channel is quite general and can be used for many cleaning protocols for primary keys in quantum cryptography.     

Transport of microparticles in weakly ionized gas-discharge plasmas under microgravity conditions

Measurements of effective structural (pair correlation function) and transport (diffusion constant) characteristics of the system of microparticles in dc and rf gas-discharge plasmas under microgravity conditions are reported. The comparison between these measurements and numerical simulations is used for complex plasma diagnostics.     

On the maximum admissible error and key compression degree in quantum cryptography on two nonorthogonal states

The extreme admissible error probability at the receiving end to which the secure key distribution is possible has been found. This result takes into account all possible attacks on the distributed key, including those that involve large quantum memory and the capability of an eavesdropper to perform collective measurements simultaneously over the entire transmitted sequence of quantum states. The critical error is independent of the parameters of a particular attack and is determined only in terms of the overlapping degree ε = |〈u₁|u₀〉¦ of information states and the fundamental functions of classical and quantum information theories. The latter functions are the capacity H(Q) of a classical binary communication channel and classical capacity \(\bar C(\varepsilon )\) of a binary quantum communication channel. The key compression degree after error correction is also expressed in terms of only the classical capacity \(\bar C(\varepsilon )\) of the quantum communication channel.     

Symmetry analysis of surface band structures in magnetic fields

The method of invariants is used to study the structure of the surface electronic energy bands in the vicinity of symmetry points in the Brillouin zone (BZ). Each of the 17 surface groups has been examined both in the presence and in the absence of spin-orbit coupling. The symmetry points for spinless particles follow a parabolic law while conic “neutrino-like” shape turns out to be the usual shape for spin −1/2 particles. Compulsory Herring degeneracy is found to occur at the sides of the BZ normal to the glide planes. The possibility of cubic rather then linear splitting in the dispersion law in the center of the BZ for groups containing 3- and 6-fold axes is demonstrated. The electron Hamiltonian for all 17 surface groups in the presence of external magnetic fields has been derived and the splitting of the degenerate energy levels in this situation has been discussed.