Products of Anodic Oxidation of Carbamide: Effect of Anionic Composition of Solution

The current efficiency for carbamide oxidation on smooth platinum electrode to molecular nitrogen and nitrate in sulfate, fluoride, chloride, and bromide solutions are determined. The supporting-electrolyte anion has a complex effect on the ratio between rates of these processes. Independence of the current efficiency from the solution pH in electrolysis of sulfate solutions of carbamide is confirmed.     

Reaction of 5-phenylpenta-2,4-dienoic acid with benzene in trifluoromethanesulfonic acid

The reaction of 5-phenylpenta-2,4-dienoic acid with benzene in CF₃SO₃H, depending on the reaction conditions, gives three products, namely, 5,5-diphenylpent-2-enoic acid and tetralone and indanone derivatives. These carbocyclic compounds are formed through the addition of two benzene molecules to the starting diene acid and subsequent intramolecular acylation.

     

Fuel Cells: State-of-the-Art and Major Scientific and Engineering Problems

Basic results of research and engineering-technical work on fuel cells (mostly membrane and methanol systems), obtained mainly in the last decade, are reviewed, with attention focused on the electrocatalytic aspect. Many works on the engineering, construction, and production of fuel cells and on the mass transfer remain outside this review, as do intrinsically theoretical works on electrocatalysis. Questions of technical and economic adaptation of these to various applications are discussed.     

Analysis of <Emphasis Type="Italic">α</Emphasis>-particle background events in a high-pressure proportional counter

The results of amplitude spectrum measurement and data processing of ²²²Rn and its daughter nucleus decays in a high-pressure copper proportional counter filled with xenon at a pressure of 14.8a tm are given. The preliminary estimates of the α/e ratio for different E/P values are also presented.     

The mechanism of tin-promoted electrochemical oxidation of organic substances on platinum

The promoting action of tin in the binary system platinum tin has been studied. A direct correlation of polarization and adsorption measurements has been carried out using an adsorption method of applying the promoter. The method of fast potentiodynamic pulses has been used to control the amount of tin and organic species on the surface. Studies have been made with smooth and platinized electrodes on the adsorption and oxidation of formic acid and methanol. A comparison of electro-oxidation rates at constant organic species coverage has made it possible to reveal the true catalytic effect as a result of introduction of tin. This effect has been found to be independent of both the nature of the substance under oxidation and the state of the electrode surface (smooth or rough). The promoting effect of tin is observed in the reactions where the limiting stage is represented by R+OH_ads; in the reactions where the limiting stage is represented by electron transfer or else the interaction R+H_ads, the promoting effect of tin does not show up, which fact points to the selectivity of its catalytic action.     

Investigation of geoeffective and non-geoeffective CMEs according to data from the URAGAN muon hodoscope

Coronal mass ejections are the brightest manifestations of solar activity. Dozens of coronal mass ejections are observed daily during periods of higher solar activity. They directly affect cosmic ray fluxes that carry information on plasma clouds, including clouds moving toward the Earth. Several aspects of geoeffective and non-geoeffective coronal mass ejections, observed with the ground-based URAGAN muon hodoscope operated as part of the NEVOD experimental complex at MEPhI, are discussed. The anisotropy of cosmic ray muon fluxes recorded during coronal mass ejections in 2014 and 2015 is investigated.     

New stage of search for 2K(2ν) capture of 78Kr

A technique to search for 2K capture of ⁷⁸Kr with a large low-background proportional counter filled with a sample of krypton enriched in ⁷⁸Kr up to 99.8% at a pressure of 4.51 atm is described in this paper. The results of first measurements are presented. An analysis of data collected for 159 h yielded a new limit to the half-life of ⁷⁸Kr with regard to 2K capture (T _1/2 ≥ 1.5 × 10²¹ yr (90% C.L.)). The sensitivity of the facility to the process for one year of measurement was evaluated to be S = 1.0 × 10²² yr (90% C.L.). The text was submitted by the authors in English.     

An experimental study of 19F-19F and 13C-19F spin-spin coupling in molecules of difluoro(fluorosulfonyl)- and difluoro(fluorosulfonyloxy)acetyl fluorides

High-resolution ¹⁹F and ¹³C NMR spectra of difluoro(fluorosulfonyl)- and difluoro(fluorosulfonyloxy) acetyl fluorides were studied, and specific features of complex spin-spin coupling of fluorine and carbon nuclei were characterized. The mechanisms of ¹⁹F and ¹³C coupling were interpreted.     

New limit on the half-life of 78Kr with respect to the 2K(2ν)-capture decay mode

The features of data accumulated for 1817 h in an experimental search for the 2K(2ν)-capture mode of ⁷⁸Kr decay are discussed. A new limit on the half-life for this decay is found: T _1/2≥2.3×10²⁰ yr (at a 90% C.L.).