Himičeskaâ fizika

This work continues the development of a new method for detecting different structural forms of biomolecules or organic compounds by analyzing hydrogen/deuterium exchange mass spectra of multiply charged (z > 1) or singly charged (z = 1) ions. The method is based on the best approximation of experimental mass spectra obtained by electrospray ionization of electrolyte solutions using a linear combination of several H/D/z distributions, assuming independent substitution of exchangeable hydrogen atoms with deuterium and independent retention of a certain number of charge carriers. The method is tested using apamin, an 18-amino acid polypeptide with a molecular mass of about 2025.886 Da. The relation between the obtained mass spectral components and the structural forms of apamin formed during hydrogen/deuterium exchange is analyzed. The comparison is made for conditions with and without the addition of ND₃-containing gas.

A mathematical model of nucleation center formation during heating of a particle of gel fuel (oil-filled cryogel based on an organic polymer thickener) in a high-temperature air environment has been developed. The model describes a group of interrelated physicochemical processes in the condensed phase and gaseous medium (inert heating, melting, separation of liquid components, their evaporation) under conditions of radiant-convective heating with source temperature variation in the range of 673–1073 K. Comparison of numerical simulation results with experimental data obtained under identical conditions has made it possible to establish the applicability of the developed mathematical model and numerical solution algorithm for predicting the achievement of dispersion conditions for a drop of gel fuel melt.

The results of initiation of pressed samples of a high explosive (HE), astralene-modified NCP ((5-nitrotetraazolato-N²)pentaammine cobalt (III) perchlorate), by radiation of semiconductor laser diodes are presented.Introduction of 0.2 wt. % of astralene into the NCP allows for a 20-fold decrease in the threshold initiation energy. It is shown that the increase of the diameter of the irradiation area of astralene-modified NCP samples from 0.13 to 2.77 mm results in the decrease of the threshold initiation energy density from 1.53 down to 0.31 J/cm².

Gyroid-type volume-structured specimens with triply periodic minimal surface topology were manufactured from AK6 aluminum alloy by selective laser melting to use them as barriers to attenuate shock waves. Stressed-strained state of gyroids and shock-wave attenuation in barrier specimens were measured by the pressure gauge. The dependencies of longitudinal stresses in the barriers on gyroid thicknesses were plotted, and shock-wave attenuation coefficients in the barriers were determined.

This work, which is mainly a review, discusses synthesis, structure and properties of catalysts comprising deposited amorphous metal nanoparticles. Considered are physical principles and features of the laser electrodispersion (LED) technique, which allows production of amorphous Pt, Pd, Ni, Cu, Au nanoparticles, as well as amorphous alloy particles such as NiPd, NiMo, NiW and deposition them on oxide, carbon and zeolites carriers. The results of studies of the catalysts structure are presented and catalysts behavior in the processes of hydrogenation, isomerization, addition, cross-coupling and others are discussed. The extremely high specific activity and stability of LED catalysts is considered in relation with the amorphous state of metal nanoparticles.