Magnetorefractive effect in granular alloys with tunneling magnetoresistance

The magnetorefractive effect and optical reflectivity are studied in granular Co-Al-O, Co-Si-O, and Co-Ti-O metal-insulator alloys exhibiting tunneling magnetoresistance for compositions close to the percolation threshold. The dependences of these effects on frequency, angle of incidence, and light polarization were measured. The experimental data obtained suggest that the major MRE mechanism in these systems is spin-dependent tunneling at optical frequencies.     

127I NQR spectra in substituted α-iodothiophenes

We have studied the complete¹²⁷I spectra and obtained the values of the quadrupole coupling constants e²Qq_zz and the asymmetry parameters in a series of substituted -iodothiophenes. Using an additive scheme, we have calculated e²Qq_zz and determined the substituent increments.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1028–1030, May, 1990.     

On the possibility of reducing the influence of laser radiation linewidth on execution of quantum logic operations using off-resonant Raman interaction

We investigate the possibility of reducing negative influence of the laser radiation linewidth on execution of quantum logical operations using off-resonant Raman interaction.     

NiII-mediated coupling between iminoisoindolinones and nitriles leading to unsymmetrical 1,3,5-triazapentadienato complexes

Treatment of nickel acetate Ni(OAc)2.4H2O with 2 equiv of various 3-iminoisoindolin-1-ones in a suspension of RCN in the presence of triethanolamine leads to the formation of the nickel 1,3,5-triazapentadienato complexes [Ni{NHC(R)NC(C6R1R2R3R4CON)}2] (1-17) isolated in good 50-83% yields. The reaction proceeds under relatively mild conditions (from 5 to 7 h at 25-115 degrees C, depending on the boiling point of the nitrile) and has a general character insofar as it was successfully conducted with various nitriles RCN bearing donor (R = Me, Et, Prn, Pri, Bun), weak donor (R = CH2Ph, CH2C6H4OMe-p), acceptor (R = CH2Cl), and strong acceptor (R = CCl3) groups R of different steric hindrance and also with the nonsubstituted iminoisoindolinone (3-iminoisoindolin-1-one) or the iminoisoindolinones bearing donor methyl (3-imino-5-methylisoindolin-1-one) or acceptor fluoro (4,5,6,7-tetrafluoro-3-iminoisoindolin-1-one) groups in the benzene ring.     

Crystal structure of Tl<Subscript>5</Subscript>{[Nb<Subscript>2</Subscript>S<Subscript>4</Subscript>Br<Subscript>8</Subscript>]Br}

By the high-temperature reaction of Nb₂S₄Br₄ and TlBr a thallium salt of the anionic cluster complex [Nb₂S₄Br₈]^4? is obtained. Its crystal structure is determined by X-ray structural analysis. The complex is also characterized by Raman spectroscopy and electrospray-mass-spectrometry.     

Simulation and study of stratified flows around finite bodies

The flows past a sphere and a square cylinder of diameter d moving horizontally at the velocity U in a linearly density-stratified viscous incompressible fluid are studied. The flows are described by the Navier–Stokes equations in the Boussinesq approximation. Variations in the spatial vortex structure of the flows are analyzed in detail in a wide range of dimensionless parameters (such as the Reynolds number Re = Ud/ν and the internal Froude number Fr = U/(Nd), where ν is the kinematic viscosity and N is the buoyancy frequency) by applying mathematical simulation (on supercomputers of Joint Supercomputer Center of the Russian Academy of Sciences) and three-dimensional flow visualization. At 0.005 < Fr < 100, the classification of flow regimes for the sphere (for 1 < Re < 500) and for the cylinder (for 1 < Re < 200) is improved. At Fr = 0 (i.e., at U = 0), the problem of diffusion-induced flow past a sphere leading to the formation of horizontal density layers near the sphere’s upper and lower poles is considered. At Fr = 0.1 and Re = 50, the formation of a steady flow past a square cylinder with wavy hanging density layers in the wake is studied in detail.     

The minimum increment of f-divergences given total variation distances

Let (P _i , Q _i ), i = 0, 1, be two pairs of probability measures defined on measurable spaces (Ω _i ,F _i ) respectively. Assume that the pair (P₁, Q₁) is more informative than (P₀,Q₀) for testing problems. This amounts to say that If (P₁,Q₁) ≥ If (P₀,Q₀), where If (·, ·) is an arbitrary f-divergence. We find a precise lower bound for the increment of f-divergences I_f(P₁,Q₁) ? I_f(P₀,Q₀) provided that the total variation distances ||Q₁ ? P₁|| and ||Q₀ ? P₀|| are given. This optimization problem can be reduced to the case where P₁ and Q₁ are defined on the space consisting of four points, and P₀ and Q₀ are obtained from P₁ and Q₁ respectively by merging two of these four points. The result includes the well-known lower and upper bounds for I_f(P,Q) given ||Q ? P||.     

Cation-anion interactions in [Mo<Subscript>3</Subscript>S<Subscript>7</Subscript>(Et<Subscript>2</Subscript>dtc)<Subscript>3</Subscript>](Et<Subscript>2</Subscript>dtc) solutions

Quantum chemical calculations of the [Mo₃S₇(Et₂dtc)₃](Et₂dtc) complex in different solvents are performed. It is shown that the binding energy between the cluster [Mo₃S₇(Et₂dtc)₃]⁺ cation and the outersphere (Et₂dtc)^? anion exponentially decreases with increase in the solvent dielectric permittivity. By DOSY NMR it is determined that in chloroform, the cationic and anionic moieties of the complex form an associate (contact ion pair), while in strongly polar dimethyl sulfoxide these moieties move independently of one another.