and a ¼ 14.0713(2),, respectively. Their crystal structures can be described as a framework of CaO 6 octahedra and V 2 O 7 pyrogroups with alkaline metals found in the tunnels formed. Photoluminescence (PL) and PL excitation spectra of the considered pyrovanadates have been studied in the vacuum ultraviolet (VUV) to visible light (Vis) range as well as their pulse cathode luminescence (PCL) spectra and the kinetic parameters of PCL. In the PL and the PCL spectra of both pyrovanadates recorded at T ¼ 300 K a broad band with maxima at 2.2, 2.4 eV and two shoulders (bands) at 2.0 and 2.58 eV have been observed. At T ¼ 10 K the band at 2.0 eV becomes the main band in the spectra. Two types of luminescence centers for each pyrovanadate, with very similar excitation bands at 3.75, 4.84, 6.2, 7.3 and 9.1 eV, have been found. The nature of the luminescence centers connected with the bands at 2.0, 2.2, 2.4 and 2.58 eV is discussed.
This paper considers some results of using tangential filtration by ceramic membrane elements for the treatment of whey. Five samples of filtrate which was obtained by four different ceramic membranes were used for experiment. These membranes have pore size 400, 200, 100, 65 and 50 nm. A semi-empirical model for the evaluation of protein retention during tangential filtration of whey using ceramic membrane elements is discussed in more detail below. The optimal membrane pore size for specified applications has been determined on the base of the proposed model. Results of the work could be used in the calculation of filtration equipment to improve the efficiency of dairy production and neutralize their waste water.
The electric power converter for downhole telemetry systems of oil-well pumps include a downhole block connected to the pump that contains electronic circuits required for the operation of the motor pump sensors and transmission of data about their condition to the surface are described. A few methods of electric power conversion for this purpose are considered. The circuit contained two steps of voltage converting are proposed. The electrical scheme of this method is considered in the article. Proposed decisions are simulated and verified experimentally. The input high supply voltage range (200-4200 V) without loss of efficiency (even temporary) was obtained. The results of simulation and experimental studies have shown very close results.
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