Synthesis of reduced graphene oxide and its electrocatalytic properties

The method of the chemical synthesis of reduced graphene oxide was developed. Sodium hypophosphite and sulfi te were used as reducing agents. The formation of reduced graphene oxide was confi rmed by several methods. Volt-ampere characteristics of electrodes based on reduced graphene oxide were investigated in an experimental model of an oxygen fuel cell with an alkaline electrolyte. Characteristics of oxygen electrodes based on reduced graphene oxide were stable over semiannual tests. The resulting reduced graphene oxide is a promising material for oxygen electrodes of chemical current sources.     

Study of DD-reaction yields from the Ti/TiO2:Dx heterostructure at low energies using the GELIS setup

The results of measurements of the DD-reaction yields from the Ti/TiO₂:D_x heterostructure in the energy range of 10–25 keV are presented. Neutron and proton fluxes were measured using a neutron detector based on He-3 counters and a CR-39 plastic track detector. A comparison with calculations showed the existence of significant effects of DD-reaction yield amplification. The screening potential for this heterostructure under these experimental conditions was estimated to be in the range U _e = 160–750 eV.     

Study of the charge distribution of galactic cosmic rays and search for superheavy nuclei traces in olivine crystals from meteorites

The search for and identification of energetic nuclei of superheavy elements of cosmic rays in olivine crystals frommeteorites, currently performedwithin the Olympia project [1], are based on measurements of dynamic and geometrical parameters of tracks, i.e., chemically etchable regions of the traces of slowing down of these nuclei before their stop, using the fully automated PAVIKOM measuring system [2].     

Fracture criterion for metal specimens with concentrators based on the theory of mean stresses

Institute of Mechanics of the Ukrainian SSR, Kiev. Moscow Aviation Institute. Translated from Prikladnaya Mekhanika, Vol. 26, No. 2, pp. 113–117, February, 1990.     

Nuclear Reactions under Irradiation of Deuterated Structures by X Rays

Measurements of emission from nuclear reaction products (neutrons and protons) have been carried out appearing in the deuterated structures of textured CVD diamond, palladium, titanium, and zirconium under irradiation with a beam of X rays using independent methods (neutron detector based on He-3 counters, Si surface-barrier semiconductor detectors and CR-39 track detector). The possibility of enhancement of both DD reaction and multi-particle deuterium fusion by the beam of X rays with energy ranging 20–30 keV in solid deuterated targets has been established. Analysis of X-ray fluorescence spectra of the target bombarded by beams of ions has revealed “additional” peaks, the occurrence of which cannot be related to any of the known elements, and requires separate study.

     

Free polarization decay in media with a short-range dipole-dipole interatomic interaction

The effect that may be exerted by an interatomic dipole-dipole interaction upon optical transient processes in dense resonance media, in particular, free polarization decay, is analyzed. The behavior of the macroscopic polarization after a single-pulse excitation of a dense ensemble of two-level atoms is considered. It is shown that the free polarization signal is of oscillatory nature, with the oscillation frequency varying in time and being dependent on the dipole-dipole interaction constant, the intensity and duration of the exciting pulse, and the detuning of its carrier frequency from the resonance. The free polarization signal decay, which depends on the magnitude and sign of the sum of the detuning of the exciting pulse carrier frequency from the resonance and the Lorentz frequency, may obey either a power or an exponential law. The signal decay rate is determined not only by the inhomogeneous broadening, but also by the ratio of the above parameters.     

Investigation of Neutron Generation upon Irradiation of Deuterated Crystalline Structures with an Electron Beam

Physics of Atomic Nuclei - The possibility of neutron generation by irradiating deuterated crystalline structures with an electron beam with an energy of 20–40 keV was studied. As targets,...     

Influence of the Flux Peaking Effect on the DD Reaction Yield Upon D + Ion Channelling in Deuterated Palladium

The interaction between a deuterium ion (D+) beam and deuterium-enriched Pd and Ti targets are studied using the HELIS ion accelerator (Lebedev Physical Institute). The neutron yield is determined from the DD reaction in the deuterated Pd target whose surface is irradiated with a D+-ion beam with an energy of 20 keV. The neutron flux is measured in the D+-ion-beam direction as a function of the angle β of target rotation relative to the beam axis using a multichannel detector based on 3He counters. Significant anisotropy (orientation effect) of the neutron yield is observed; it is two times higher at β = 0° than at β = ±30°. The orientation effect can be associated with channeling and the so-called flux-peaking effect. It is studied by computer simulations using the BCM-2.0 code. The enhanced density of the D+ flux between the (200) planes of a Pd crystal (where implanted D is located) at zero angle of incidence with respect to these planes makes it possible to qualitatively explain the observed orientation effect. No effect is observed in a homogeneous target of deuterated titanium.     

Electrocatalytic properties of multiwalled carbon nanotubes-based nanocomposites for oxygen electrodes

Metals (platinum, nickel, and lead) and oxides (manganese dioxide and molybdenum, chromium, cobalt, and niobium oxides) were deposited onto multiwalled carbon nanotubes by chemical and electrochemical methods. The resulting nanocomposites were tested as oxygen electrode materials for electrochemical power sources with alkaline electrolytes. A correlation was revealed between the catalytic activity of oxygen electrodes manufactured from composites based on carbon nanotubes with catalyst deposited, on the one hand, and the coefficient a in the Tafel equation for the oxygen evolution reaction on this catalyst, on the other. A possibility of predicting and evaluating the catalytic properties of oxygen electrode materials for power sources was suggested.