Thermal decomposition of bis[carbonyl(μ-alkyl(aryl)thio)η5-cyclopentadienyliron] complexes

Conclusion The thermal decomposition of [FeCp(SR)CO]₂ complexes, where B is Et or Ph, leads to ferrocene and a mononuclear complex, FeCpSE(SO)₂. Stable polynuclear complexes are not formed.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 655–657, March, 1987.     

Diffusion of point defects participating in solid-phase chemical reactions (trap diffusion): Demonstration for the Ti3+ → Ti4+ transition in corundum

A problem of trap diffusion, that is diffusion of point defects in crystals participating in a solid-phase chemical reaction with motionless impurity ions, is solved. Time dependences of the reaction-front displacement, X_f, and its steepness, $\text{(}\text{?C}\text{?X}\text{)}{}_{\mathrm{f}}$ are determined analytically for N₀ ? C₀ and numerically for all relations of N₀ and C₀$\text{x}{}_{\mathrm{f}}{}^2\text{=2}\text{N}{}_0\text{C}{}_0\text{Dt; (}\text{ac}\text{ax}\text{)}{}_{\mathrm{f}}\text{=0.3C}{}_0{}^{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{(}\text{g}\text{D}\text{)}{}^{\mathrm{<mtext>1</mtext><mtext>2></mtext>}}$where C₀ and N₀ are the initial concentration of impurity and the eqilibrium defect concentration, respectively, D is a diffusion coefficient, and g is a chemical reaction constant. Dependence of X_f vs C₀ and t is confirmed for oxygen annealing of corundum crystals doped with titanium which, reacting with the point defects, changes its valency. The data are obtained for dependence of displacement X_f upon partial oxygen pressure and thermotreatment temperature as well as upon the sign of the constant electric field applied to the sample. From these data we conclude that the reaction of titanium impurity, changing from the three-valent to the tetravalent state at the activation energy of 80 ± 8.5 kcal/mole is due to anisotropic diffusion of charged aluminum vacancy and holes in the valence band. The diffusion coefficient for that process at 1500°C is estimated to be larger than 10^?5 cm²/sec. Using the trap-diffusion features, the concentration of optical centers of the 0.315-μm absorption band in ruby is also estimated.     

On some properties of cascade processes with random intensity

By the example of the asymptotically free theory λϕ ₆³ with random constant λ, the process of cascade multiplication of particles with random intensity of elementary decay is considered. The dependence of the characteristics of the cascade particle multiplicity distribution on the parameters of the probabilistic distribution over the elementary decay intensity is studied.     

Synthesis and properties of hydrocarbons of mixed structure and high molecular weight

Russian Chemical Bulletin -     

Investigation of laser-induced depth damage and scattering of light in crystals and glasses

Laser-induced depth damage to sapphire crystals and to various glasses is investigated. The influence of self-focusing on the laser damage process is studied. The conditions under which self-focusing influences the damage are clarified. The influence of various impurities on the optical endurance of ruby laser crystals is determined. The damage mechanism is initiated by various types of absorbing inclusions and defects; a correlation is found between the light scattering and the damage threshold. A new criterion based on light scattering is introduced for the purity of transparent dielectrics.Translated from Trudy Ordena Lenina Fizicheskogo Instituta im. P. N. Lebedeva, Vol. 101, pp. 31–74, 1978.     

Synchronous ultrasonic Doppler imaging of magnetic microparticles in biological tissues

We considered applicability of acoustic imaging technology for the detection of magnetic microparticles and nanoparticles inside soft biological tissues. Such particles are widely used for magnetically targeted drug delivery and magnetic hyperthermia. We developed a new method of ultrasonic synchronous tissue Doppler imaging with magnetic modulation for in vitro and in vivo detection and visualization of magnetic ultradisperse objects in soft tissues. Prototype hardware with appropriate software was produced and the method was successfully tested on magnetic microparticles injected into an excised pig liver.     

Moment analysis of multiplicity distributions

Moment analysis of global multiplicity distributions previously done for e ⁺ e ^? and hh processes is applied to hA and AA collisions. Oscillations of cumulants as functions of their rank are found in all processes for which experimental data are available. A similar oscillation pattern is found in the dual parton model and quark-gluon string models but not in the phenomenological fits such as modified negative binomial distributions. The zeros of the truncated generating function move closer and closer to the unity circle in the complex z-plane when the complexity of the collision increases.     

Moments of the very high multiplicity distributions

In experiment, the multiplicity distributions of inelastic processes are truncated due to finite energy, insufficient statistics, or special choice of events. It is shown that the moments of such truncated multiplicity distributions possess some typical features. In particular, the oscillations of cumulant moments at high ranks and their negative values at the second rank can be considered as ones most indicative of the specifics of these distributions. They allow one to distinguish between distributions of different type.     

Cascades of atomic displacements in solids: The ballistic stage

The evolution of cascades of atomic displacements in solids is analyzed. The charge-exchange, ionization, and elastic scattering cross sections are calculated for the atoms and ions involved in cascade evolution. The effects due to the material density are taken into account. These results are used to perform the first Monte Carlo computations of cascades based on the knowledge of microscopic processes without invoking phenomenological potentials. The proposed approach is unique in that detailed characteristics of atomic processes are obtained by ab initio calculation and applied to analyze cascades of atomic displacements. Subcascade development is described, and a relation between the number of Frenkel pairs and the energy of the primary knock-on atom is found for a wide energy range. This provides a basis for characterizing the dose dependence of the hardening of reactor pressure vessel steel and for comparing the effects of primary radiation damage for fission and fusion reactors.