Energy spectra of secondary particles in γ families and their sensitivity to the spectrum of primary cosmic rays

Spectra of secondary particles (γ-rays) in γ-families detected in the X-ray chambers in the Pamirs (H = 600 g cm^?2) have been analyzed. These γ-ray spectra show a bend at the energy E* _γ ≈ (ΣE _γ )^min, where (ΣE _γ )^min is the lowest total energy of γ-rays in the families above which γ-families were selected. The bend is not related to the knee in the spectrum of primary particles; it is due to the use of the ΣE _γ selection criterion. The E _γ spectrum slope is sensitive to the spectrum of the primary cosmic rays in the region E _γ ≥ (ΣE _γ )^min.     

Electrophilicity Indices for Peroxyl Radicals

In this work, electrophilicity indices are calculated for 50 peroxyl radicals with density-functional theory (B3LYP hybrid functional and the 6-311+G(d,p) basis set). There is a relationship between general and local electrophilicity indices of peroxyl radicals and Taft inductive constants (σ*) of the substituents at the–OO^? group.     

Reactivity of Cyclohexanol CH Bonds toward the tert-Butylperoxy Radical

The effect of the hydroxy group on the partial rate constants of the reactions of the tert-butylperoxy radical with CH bonds in cyclohexanol at 333 K was studied by the Howard–Ingold method. The overall reaction rate constant increased with decreasing alcohol concentration in chlorobenzene because of complex effects of hydrogen bonds at the steps of chain growth and termination. The hydroxy group activates the -CH bond and deactivates the - and -CH bonds. The reactivity of -CH bonds is close to the reactivity of CH bonds in cyclohexane.     

Frequency dispersion of the dielectric characteristics in polymer films based on the [NiSalen] complex

The results of the measurements of the dielectric properties exhibited by metal-containing polymer structures based on Ni(II) complexes in the frequency range f = 10²–10⁵ Hz are reported. It is established that, in the range of acoustic frequencies, the permittivity ε decreases with increasing frequency, whereas the dielectric loss tangent tan δ increases. At frequencies f > 10⁴ Hz, the dependence tan δ(f) is characterized by a relaxation maximum. The possible mechanisms of dielectric polarization and charge transfer in an alternating-current electric field are considered.     

High-speed videocamera investigation of the wave structure development on an unstable cavity boundary

The formation of wave structures on an unstable (in the Rayleigh-Taylor criterion) boundary of a plane cavity is studied using high-speed video filming. It is shown that at the head of the cavity a quasiperiodic wave regime develops, with a mean wavelength similar to that obtained from a linear stability analysis for the cavity boundary. Observations of the initial-regime breakdown show that its scenarios are similar to the development of subharmonic instability in the one-mode regime. The waves are classified with respect to the wave development rate. It is shown that the large-wave amplitude growth law is on average closely approximated by a quadratic parabola, with the total gas entrainment from the cavity being proportional to the square of the cavity length. The existence of a scaling effect is detected, which in the case considered reduces mainly to a dependence of the gas entrainment coefficient on the Weber number. It is shown that with decrease in the Weber number the gas entrainment coefficient may significantly increase.     

Evaluation of the Reactivity of Cyclohexanone СН Bonds in Reactions with tert-Butylperoxy Radical by Quantum Chemical Methods

Kinetics and Catalysis - The effective charges on hydrogen and carbon atoms and the Fukui functions for the electrophilic and radical attacks for the hydrogen atoms of the chair and boat...