Analysis of the Results of the Neutrino-4 Experiment on the Search for the Sterile Neutrino and Comparison with Results of Other Experiments

JETP Letters - New measurements of the flux and spectrum of reactor antineutrinos as functions of the distance from the center of the core of the SM-3 reactor (Dimitrovgrad, Russia) in the range of...     

Propylene Radical Copolymerization

Unlike ethylene, which is quite active in radical poly- and co-polymerization, the next member of the olefinic row–propylene (Pr)–is much less efficient in such reactions. Thermodynami-cally, the polymerization of Pr is permitted as is evidenced by reactions with Ziegler-Natta catalysts (The free energy change δG for the conversion of liquid Pr into amorphous poly-Pr at 25°C is -12.2 kcal/mol [1].), but the strong chain transfer activity of the Pr-monomer prevents formation of high molecular weight polymers via radical mechanism. Pr easily gives up H″ atoms with the formation of inactive and probably resonance stabilized allyl radicals CH₂[sbnd]CH[sbnd]CH₂ .(The high resonance stabilization of the Pr-radi-cal 'CH₂ CH[dbnd]CH₂, formed after separation of the H″ atom, should not be confused with a very low resonance stabilization of the Pr-radical 'CH₂ [sbnd]CH[sbnd]CH₃, formed after opening of the double bond. The Q–e scheme deals with the second type of radical and Pr is characterized by a low resonance factor, Q_pr 0.002.) As a result, Pr radical homopolymerization gives low-molecular weight polymer (even at a pressure of 15,000 atm the molecular weight of poly-Pr is only ～3000 [2, 3]).     

Investigation of the piezoelectric constants of polycrystalline ferroelectrics of the barium titanate type

A study has been made of the piezoelectric constants of polycrystalline ferroelectrics of the barium titanate type and of their dependence on temperature of sintering of the ceramic and on the constant voltage applied. The measurements were made under static and dynamic conditions. It is shown that the piezomoduli of certain solid solutions in the systems Ba(Ti, Zr, Sn)O₃ and Ba(Ti, Si, Sn)O₃ are somewhat greater than those of barium titanate.     

Metastable phases in YBCO films created by short-term annealings

The effect of short-term low-temperature annealing in air and in vacuum on the properties of HTSC films of YBCO is studied. It is shown that, under certain conditions of preparation of initial samples, a transition from the HTSC phase with the superconducting transition temperature T_c=90 K to a phase with T_c=60 K occurs without a noticeable change in the oxygen content. It is found that, as a result of short-term annealings, a transition from the HTSC phase with T_c=60 K to the phase with T_c=90 K can occur only through the vacuum annealing stage, which converts the sample into the superconducting state. Short-term annealings lead to multiple reversible “switching” of the films from one phase to another. The obtained results are of practical interest, since the proposed method can be used to quickly obtain superconducting YBCO films in various phase states. It is shown, in addition, that the annealing procedure makes it possible not only to increase the oxygen concentration but also to produce a structural rearrangement of a YBCO film.     

Formation of Optimal Working Space in Adsorbers with Fixed and Moving Adsorbent Beds

The possibility of improving the adsorbent efficiency by means of transverse, longitudinal sectioning of adsorption apparatus is substantiated. Results of an experimental and calculation study of sectioned apparatus are presented. A number of designs of sectioned adsorbers with the optimal working space were developed.     

Specific features of operation of a reaction-rectification column in different feed modes

Various feeding modes (discrete and distributed) into a reaction-rectification column for production of ethylene glycol are analyzed.     

A process for production of granulated soluble glass in ore-thermal furnaces

A process for production of soluble sodium glass in electric-arc ore-thermal furnaces with three graphite electrodes was suggested and tested on the industrial scale. Fusion of sand with sodium carbonate, followed by rapid cooling of the fusion cake with cold water, yields finely grained sodium metasilicate with a developed network of microcracks as a result of a thermal impact in the course of aqueous granulation of the fusion cake.