Electrodynamic acceleration of small conducting particles

The possibility of separation of conducting submillimeter particles from nonconducting elements of a friable rock is theoretically substantiated in the present work. It is suggested to accelerate particles upon exposure to a nonstationary and nonuniform magnetic field created by a system of magnetic coils. Approximate analytical expressions for the velocity of a conducting particle are derived in the paper for the simplest configuration of fields of two induction coils. It is demonstrated that in the present stage of development of high-current electronics, it is technically possible to obtain the velocity of translational particle motion of a few tens of centimeters per second. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 90–95, January, 2008.     

Mechanism of oxidation of xylenes with Pd(II) complexes

Conclusions Oxidation of xylenes with Pd(II) complexes in acidic medium is possible according to two pathways: a) electrophilic substitution in the arene ring with the formation of an organometalic intermediate and b) one-electron transfer from the arene to the palladium atom with the intermediacy of the arene cation-radical. The relative contribution of each pathway depends on the nature of the arene and on the acidity of the medium.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2167–2174, October, 1985.     

Spectroscopy of the heavy resonances ρ′, ρ″, ω′ and ω″

The spectroscopy of the isovector resonances ρ′ and ρ″ and the isoscalar resonances ω′ and ω″ is considered on the basis of their masses and coupling constants extracted from data on e ⁺ e ^? annihilation, τ-lepton decays, and the reaction K ^? p → π ⁺ π ^?Λ. The total widths of these resonances and the branching fractions for their decay modes are calculated. It is argued that the shift of the apparent position of the peak in the energy dependence of the cross section with respect to the bare mass is significant for broad resonances. The results are compared with the predictions of available models for the ρ′, ρ″, ω′, and ω″ resonances.     

On the relationship between the deuteron form factors and the physical S matrix. I

Conclusions The present paper has been devoted primarily to kinematics. In the next paper the results we have obtained will be used for a realistic calculation of the form factors of the bound state of the n-p system-the deuteron.Two results are of independent interest. First, the inequality of the initial, , and final, , masses of the n-p system and the parametrization (28) result in the appearance of the transition form factor f₂₁ (–), which, generally speaking, makes a contribution to the matrix element pn|j|pn and also to the electrosplitting of the deuteron [15]. Secondly, we have found an admixture of the magnetic form factors of the proton and neutron in the charge form factor of the n-p system. This admixture will also be retained in the charge form factor of the deuteron. This mixing is due to the relativistic spin rotation and may be important in the solution of the problem that is the inverse of that we have been considering-the determination of information about the electromagnetic form factors of the neutron from the known form factors of the deuteron and proton. Since the experimental charge form factor of the neutron is small in magnitude, the calculated value of G_Ep is very sensitive to theoretical and experimental corrections (see, for example, [16]).M. V. Lomonosov Moscow State University. V. A. Steklov Mathematics Institute, Academy of Sciences of the USSR. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 10, No. 1, pp. 45–57, January, 1972.     

Maxwell equations in conformal invariant electrodynamics

We consider a conformal invariant formulation of quantum electrodynamics. Conformal invariance is achieved with a specific mathematical construction based on the indecomposable representations of the conformal group associated with the electromagnetic potential and current. As a corollary of this construction modified expressions for the 3-point Green functions are obtained which both contain transverse parts. They make it possible to formulate a conformal invariant skeleton perturbation theory. It is also shown that the Euclidean Maxwell equations in conformal electrodynamics are manifestations of its kinematical structure: in the case of the 3-point Green functions these equations follow (up to constants) from the conformal invariance while in the case of higher Green functions they are equivalent to the equality of the kernels of the partial wave expansions. This is the manifestation of the mathematical fact of a (partial) equivalence of the representations associated with the potential, current and the field tensor.     

Application of a cryogenic moderator in the REMUR neutron reflectometer

Examples of the application of a cryogenic moderator in the REMUR time-of-flight neutron reflectometer of the IBR-2 pulsed reactor (Dubna) are given. The results of two experiments are presented: spatial beam splitting upon reflection from a magnetically noncollinear film and the recording of a microbeam formed by a layered waveguide. A conclusion concerning the efficiency of the cryogenic moderator for experiments of this type is made.     

Thermodynamic properties of nonstoichiometric oxygen in manganite Ca<Subscript>0.9</Subscript>Pr<Subscript>0.1</Subscript>MnO<Subscript>3–δ</Subscript>

The chemical potential of oxygen Δμ_O relative to its standard state in the gas phase was calculated from the experimental dependences of the oxygen content in various polymorphic modifications of Ca_0.9Pr_0.1MnO_3–δ on the partial pressure and temperature. The partial molar enthalpy \(\Delta {\overline H _O}\) and entropy \(\Delta {\overline S _O}\) of oxygen were obtained from the linear temperature dependences of Δμ_O. Based on the ideal solution approximation, \(\Delta {\overline H _O}\) and \(\Delta {\overline S _O}\) were correlated with the enthalpies and entropies of the defect formation reactions, the concentrations of manganese cations, and the oxygen nonstoichiometry. The thermal excitation of Mn⁴⁺ cations was shown to substantially affect the thermodynamic functions of oxygen.     

Electronic and magnetic structures and conductivity of strontium ferrite: An ab initio LSDA + U approach

Using the first-principle nonempirical linear muffin-tin orbital method in the tight-binding approximation (TB-LMTO) to the LSDA + U approximation, the electronic and magnetic structures and defect formation in strontium ferrite Sr₃Fe₂O₆ are studied. It is found that Sr₃Fe₂O₆ is a G type antiferromagnetic with the semiconductor electronic structure. The calculated band gap of 1.82 eV agrees well with experimental value (～2 eV). The ferrite spectrum corresponds to that of a semiconductor with a band gap of charge transfer. Iron ions in Sr₃Fe₂O₆ are in a high-spin state and have configuration t _2g ^↑3 e _g ^↑2 e _g ^↓1 . The calculated local magnetic moment on the iron ions is 3.9 μ_B. The presence of iron ions with a magnetic moment approaching 4 μ_B in Sr₃Fe₂O₆ is explained by strong hybridization of 3d orbitals of iron and 2p orbitals of oxygen. The high-spin state of iron ions is described by d ⁵ + d ⁶ L states with predominant contribution d ⁶L, where L is a hole on oxygen. Based on ab initio LSDA + U calculations, various types and configurations of defects in the oxygen sublattice (oxygen vacancies, anti-Frenkel defects) are studied and a model for ionic transport in Sr₃Fe₂O₆ is proposed.