Anomalous thermopower in the metalliclike phase of a 2D hole system

We report very low temperature ( T) thermopower and resistivity ( rho) measurements on variable-density, two-dimensional hole systems confined to GaAs quantum wells. As the hole density is lowered from 1.49x10(11) cm(-2) to 0.14x10(11) cm(-2), the system crosses from an insulating ( drho / dT less, similar0) to a metallic regime ( drho / dT>0) and finally displays insulating behavior ( drho / dT<0). Diffusion thermopower shows a striking sign reversal in a narrow range of density in the metallic regime, suggesting a qualitative change in the conduction or the scattering mechanism.     

The effect of external perturbing moments on the dynamics of a uniaxial single-flywheel attitude control system of a spacecraft PMM vol. 31, no. 6, 1967, pp. 1095–1103

Effective damping of relative craft oscillations in a single-flywheel uniaxial attitude control system whose purpose is to keep a spacecraft oriented in some direction in space, e.g. towards the Sun, can be achieved by nonrigid coupling of its body with the axis of rotation of the flywheel [1]. This can be accomplished by adequately restricting two of the degrees of freedom of the flywheel in a three-degree universal suspension by means of a proportional damper of any type.

In the present paper we shall consider the stability of free oscillations of a spacecraft equipped with a flywheel on a movable axis, as well as the motion of tlie oriented craft axis under the action of external perturbing moments and the perturbed motion of the craf itself relative to the oriented axis.     

Neospiroenones. Synthesis of 10,11-dimethoxy-1,6,6-trimethyl-5,6,8,12b-tetrahydrobenzo[d,f]indol-4(3H)-one and 10,11-dimethoxy-6,6-dimethyl- 1,5,6,12b-tetrahydrobenzo[d,f]indol-2(8H)-one

The three-component condensation of isobutyraldehyde, 3,4-dimethoxyphenylacetonitrile, and p-methylanisole or anisole in the presence of concentrated sulfuric acid affords neospiroenone systems.     

Elementary heterogeneously polarized field modeling

An approach for experimental modeling of elementary field cells with heterogeneous polarization is proposed. It is shown that such cells may be obtained by the superposition of orthogonally linearly polarized waves with relatively simple phase surfaces and close intensities. The experimental arrangement for obtaining elementary field cells is suggested. The characteristics of a polarization cell may be easily changed by the change of superposed beam parameters. The results of experimental investigation are presented.     

Magnetic properties of rare-earth β-enaminoketone metallomesogens

Reaction of β-enaminoketones with lanthanide salts leads to mesomorphic complexes displaying an S_A mesophase. The mesophase was characterized using X-ray scattering, EPR and magnetic susceptibility. A very high magnetic anisotropy was deduced for a complex containing dysprosium.     

Adsorption of cationic and nonionic surfactants on a SiO<Subscript>2</Subscript> surface from aqueous solutions: 2. Adsorption of dodecylpyridinium bromide and Triton X-100 from mixed solutions

Adsorption of cationic (dodecylpyridinium bromide) and nonionic (Triton X-100) surfactants from their mixed aqueous solutions on a SiO₂ surface at pH 3.6, 6.5, and 10 is studied by the UV spectroscopy, capillary zone electrophoresis, and wetting measurements. It is shown that the adsorption of cationic and nonionic surfactants from mixed solutions is accompanied by synergistic effects manifesting themselves as an enhanced adsorption of both surfactants compared to their adsorption from individual solutions. The effect of second component becomes most pronounced under conditions when differences in adsorption abilities of individual surfactants are rather large (at pH 3.6 and 10). It is shown that the adsorption of surfactants from mixed solutions can be controlled by the adsorption ability of components via the variations in solution pH.__________Translated from Kolloidnyi Zhurnal, Vol. 67, No. 2, 2005, pp. 281–287.Original Russian Text Copyright © 2005 by Kharitonova, Ivanova, Summ.