Relaxation time estimates for multipath catalytic reactions

Some results of studying the dynamic behavior of multipath catalytic reactions are given. Finitely and infinitely slow relaxations to stable stationary states were distinguished, and some relaxation time estimates are presented.     

Simulation of the xenon gamma spectrometer for analyzing radioactive materials

The results of the calculation of the detection efficiency of gamma-rays for the xenon gamma spectrometer (XGS) obtained using the GEANT4 Monte Carlo simulation are presented. The gamma spectra of the set of basic standard gamma-sources (OSGI) are analyzed for a real detector, and the calculated and actual detection efficiencies are compared. The XGS spectra are analyzed to determine the minimum concentration of the ¹⁵²Eu radio nuclide in the ¹³⁷Cs and ⁶⁰Co mixture. It is shown that the xenon gamma spectrometer is capable of detecting the isotope at concentrations above 40% in the mixture.     

Internal conversion as the main stabilization mechanism for long-lived negative molecular ions

The temperature dependence of the mean lifetime of Ph-N=N-Ph^? azobenzene negative molecular ions on the captured electron energy is studied with a static mass spectrometer by the method of resonance electron capture. A family of respective experimental dependences is calculated accurate to 2–10%. It is shown that the molecular anions in the epithermal electron energy range can be stabilized through internal conversion, namely, a series of fast radiationless transitions without change in the multiplicity.     

Polarity of an МСМ-41 adsorbent surface modified with methyl and phenyl groups based on data from gas chromatography

The polarity of an MCM-41 adsorbent surface and organosilylated composites based on it with grafted trimethylsilane and dimethylphenylsilane groups is studied via inverse gas chromatography at infinite dilution. The dispersion and specific components of the value proportional to the Helmholtz adsorption energy are calculated, and a comparative analysis of the surface polarity of MCM-41 and its modified analogs relative to the commercially available C-120 silica gel is performed. The electrostatic and donor–acceptor components of the specific Helmholtz adsorption energy are calculated through linear decomposition of the adsorption energy. It is established that MCM-41 is less polar than C-120. The modification of the initial adsorbent surface leads to a reduction in polarity, due mainly to the weakening of induction and orientation interactions. It is concluded that the surfaces of the modified samples retain the ability to form hydrogen bonds.     

Numerical differentiation on scattered data through multivariate polynomial interpolation

BIT Numerical Mathematics - We discuss a pointwise numerical differentiation formula on multivariate scattered data, based on the coefficients of local polynomial interpolation at Discrete Leja...