Combination dryer with a vortical bed for dewatering a suspension of MCM copolymer

Chemical and Petroleum Engineering -     

Optical and electrical properties of polyamide acid and metal-polymer complex based on terbium

The basic optical and electrical properties of polyamide acid and its complex with Tb⁺² have been studied. The occurrence of room-temperature photoluminescence (PL) with an emission peak at 520 nm is established. The activation energy of conductivity at temperatures above 350 K is 2.1 eV. Polyamide acid is comparable in PL intensity with an electroluminescent polymer, poly(p-phenylvinylene).     

Present Status and Future Prospects of the Work on the Moscow Meson Factory

The current status and prospects of work on the Moscow meson factory are described. The maximum energy obtained at the present time is limited by the existing powerful klystrons and is 247 MeV. The maximum beam intensity is 150 A. The accelerator beam is used for fundamental research and for solving applied problems. The average duration of the sessions is 2000 h per year. Three of the five branches of the proton channel which are provided in the design are in operation in the experimental complex. This includes the branch on the multifunctional neutron complex, which is to be used for, among other things, research on nuclear transmutation of long-lived fission products, Np, Am, Cm, and the electronuclear method of generating electricity. The first phase of the proton therapy complex is under construction.     

The Superconducting Bismuth-Based Mixed Oxides

The present paper describes the synthesis, characterization of mixedvalence bismuthates with 3- or 2-dimensional perovskite-like structures and structural criteria that influence superconductivity in these compounds. Single phase samples of Sr_1–x K _x BiO₃ were prepared for the broad range of K-content: 0.25x0.65. For these bismuthates the symmetry of the structure changes from monoclinic to orthorhombic and finally to tetragonal upon increasing the K-content thus resulting in the decrease of the Bi-O distances and reduction of the network distortions. Superconductivity with maximum T _c=12K exists in the narrow range (x0.5–0.6) within the stability field of the tetragonal phase (0.33x0.65), when the 3-dimensional octahedral framework has close to the ideal perovskite structure arrangement. At the same time compositions with close to optimal Bi-valence (x=0.33 and 0.43) do not show any sign of superconductivity, probably, due to structural distortions. The layered type (Ba, K)₃Bi₂O₇ and (Ba, K)₂BiO₄ bismuthates belonging to the A _n+1B _n O_3n+1 homologous series were investigated. Buckling of the (BiO₂) layers in the structure of the n=2 member was revealed. The formation of the n=1 bismuthate was found by Electron Microscopy and X-ray powder diffraction studies. Both types of compounds are considered to be possible candidates for new superconducting materials among bismuthates.     

Queueing Networks with Multichannel Nodes and Recurrent Input Flow

Queuing networks with GI|GI|-type nodes are considered. By the renewal theory methods, the conditions of existence of the stationary mode are found and asymptotic properties of multivariate binomial moments are studied. For binomial moments of any degree, a recurrent moment finding scheme is proposed. In the case of the [GI|GI| ]^r-networks operating in the stationary mode, the extended Jackson law is proved.     

On the Similarity Criteria for the Processes of High-Temperature Sulfur Corrosion of Heat-Resistant Alloys

A similarity parameter for the high-temperature sulfur corrosion of heat-resistant alloys is suggested. This parameter allows to put in order published experimental data of different authors. Original data on the weight loss by 826, -70, 26, and several materials for protective coatings also correlate with the similarity parameter. The dependences thus obtained allow to predict the operation life of materials (by their weight loss) and to rank nickel-based alloys by their corrosion resistance, depending on their elemental composition.