A generalised model and calculation of the hyperfine interaction constant for anomalous muonium in the crystalline lattice of silicon

A new microscopic model of anomalous muonium for the elemental semiconductors is proposed. The relevant configuration consisting of both a diamagrentic molecule Si−Mu and an unpaired orbital e⁻ is contained into a semivacancy of the real lattice. By using the unrestricted Hartree-Fock computational method the principal properties of the system are established. A dynamical version of the model together with a question on the formation of such system are discussed.     

Resistance of composite flywheel rim to radial tensile stresses from centrifugal forces based on results of pure bending of a rim segment

A method is proposed for evaluating the resistance of a flywheel rim to radial stresses in free rotation. The method is based on loading a rim segment in pure bending and calculating the limiting moment and the corresponding limiting angular velocity. Applicability of the method is substantiated theoretically by investigating the similarity of the radial stress diagrams in rotation and pure bending. The method is verified experimentally for the strained state of a rim segment in pure bending.Translated from Mekhanika Kompozitnykh Materialov, Vol. 29, No. 4, pp. 521–526, July–August, 1993.     

Isotopic study of the mechanism of ozone formation

The mechanism of ozone formation has been studied using ¹⁶O and ¹⁸O₂. High-resolution microwave spectroscopy was used to measure the amounts of the isotopomeric ozone species formed. The study is hampered by the very rapid exchange process between the reactants, that tends to scramble the isotopes and hence give a 2:1 statistical ratio between the two possible isotopomers. We have found a strategy to come around this difficulty and conclude that the mechanism is a simple end-on-addition.     

Temperature dependence of the rate constants for reactions of the carbonate radical with organic and inorganic reductants

Rate constants have been measured by pulse radiolysis for the reactions of the carbonate radical, CO₃^·?, with a number of organic and inorganic reactants as a function of temperature, generally over the range 5 to 80°C. The reactants include the substitution-inert cyano complexes of Fe^II, Mo^IV, and W^IV, the simple inorganic anions SO₃^2?, ClO₂^?, NO₂^?, I^?, and SCN^?, several phenolates, ascorbate, tryptophan, cysteine, cystine, methionine, triethylamine, and allyl alcohol. The measured rate constants ranged from less than 10⁵ to 3 × 10⁹ M^?1 s^?1, the activation energies ranged from ?11.4 to 18.8 kJ mol^?1, and the pre-exponential factors ranged from log A = 6.4 to 10.7. The activation energies for the metal complexes and inorganic anions generally decrease with increasing driving force for the reaction, as expected for an outer sphere electron transfer. For highly exothermic reactions, however, the activation energy appears to increase, probably reflecting the temperature dependence of diffusion. For many of the organic reactants, the activation energies were low and independent of driving force, suggesting that the oxidation is via an inner sphere mechanism.     

The inclusion of electrostatic and dispersion interactions into potentials of mean torque for solutes dissolved in uniaxial liquid crystal solvents

A potential of mean torque is derived for a solute at infinite dilution in a uniaxial liquid crystal solvent, which contains terms originating from the dispersion interaction, and the electrostatic interaction between quadrupole moments on both molecules. It is shown that the electrostatic term is non-zero only if the solute-solvent vectors are distributed with lower than spherical symmetry. If this distribution has cylindrical symmetry then both the electrostatic and dispersion terms in the potential of mean torque are shown to depend on order parameters for the orientational distribution of the solute-solvent vectors, as well as on the order parameters of the solvent molecules.     

Evaluation of peroxyoxalate chemiluminescence postcolumn detection of fluphenazine in urine and blood plasma using high performance liquid chromatography

Peroxyoxalate chemiluminescence may be used for sensitive postcolumn detection of phenothiazine analytes separated by high performance liquid chromatography with appropriate optimization of measurement conditions such as solvent, pH and oxalate ester. Detectability of fluorescent analytes by chemical excitation varies greatly, but analytes with low oxidation potentials are generally more readily detected at low levels, as demonstrated for phenothiazines, an important class of fluorescent drugs. Some improvement in detection limits is observed for fluphenazine when chemiluminescence detection is compared to conventional fluorescence detection. Because of the specificity of chemical excitation, fewer interferences from fluorescent impurities in a urine matrix are observed.