Detection of cracks under threads of studs of power equipment and drill pipes during ultrasonic testing

Special features of finding cracks under threads of drill pipes and studs of power equipment are considered. Standard angle single-crystal probes, a special normal dual probe, and a probe of head waves were used for ultrasonic testing. They were compared and their efficiency was estimated. The succession of tuning of the scan duration, the depth gage, and the sensitivity of the probe is described.     

Kaolins for production of sanitary ceramics

Several types of kaolins from different manufacturers were investigated. The chemical, mineral, and granulometric compositions of the kaolins and their effect on the properties of the finished pastes were investigated. The properties of kaolins required for optimizing the properties of ceramic pastes were determined. The rheological characteristics were examined and their effect on control of the manufacturing process were examined. The basic drawbacks and advantages of the different types of kaolins, both those traditionally used by domestic manufacturers and some new ones, were established.     

Smelting low-silica hot metal at OAO NTMK

In the blast-furnace shop at OAO Nizhnetagil’skii Metallurgicheskii Kombinat (NTMK), the smelting of low-silica vanadium hot metal is being introduced. Theoretical and experimental data reveal the influence of the pressure in the furnace’s working space and coke quality on the reduction of titanium and the formation of refractory titanium compounds. The residence time of the melt in the hearth depends on its dimensions.     

Initiation of luminol chemiluminescence by two-quantum excitation of U(IV) in aqueous solution

Results of experiments on initiation of luminol chemiluminescence by multiquantum excitation of U(IV) in aqueous solution by dye laser radiation in the visible range are reported.     

Jacobi’s bound for independent systems of algebraic partial differential equations

In this paper we prove Jacobi’s bound for systems of n partial differential polynomials in n differential variables, which are independent over a prime differential ideal \mathfrakp{\mathfrak{p}} . This generalizes on the one hand our result (Kondratieva et al. in On Jacobi’s bound for systems of differential polynomials, algebra. Moscow University Press, Moscow, pp 79–85, 1982) about Jacobi’s bound for ordinary differential polynomials independent over a prime differential ideal \mathfrakp{\mathfrak{p}} and, on the other hand, the result by Tomasovic (A generalized Jacobi conjecture for arbitrary systems of algebraic differential equations. PhD thesis, Columbia University, 1976), who proposed a version of Jacobi’s bound for partial differential polynomials and proved it in the linear case. In Kondratieva et al. (Differential and difference dimension polynomials, Kluwer, Dordrecht, 1999) we gave another proof of this result by Tomasovic. The exposition in the present paper follows our proof in Kondratieva et al. (Differential and difference dimension polynomials, Kluwer, Dordrecht, pp 273–280, 1999).     

Parameters of free radical oxidation in blood plasma of women from the Alta? region

The minimum inhibitory concentrations of 39 Helicobacter pylori strains against antibiotics (ampicillin, tetracycline, metronidazole), colloidal bismuth subcitrate and proton pump inhibitors were assessed by the agar dilution method. 20.5% of the strains were metronidazole resistent. The comparison of the bactericidal action of omeprazole and lansoprazole in a killing curve assay showed a dose-dependent reduction of viable bacteria after 24 h, lansoprazole being more effective than omeprazole. Under varying pH conditions, the antibacterial activity of lansoprazole was limited to a pH range of 6-7, reducing bacterial numbers up to 4 logarithmical steps within 24 h.