X-ray electron spectroscopic investigation of the structure of double lead silicate glasses

The method of x-ray electron spectroscopy is used to investigate lead silicatexPbO(1 -x) · SiO₂ (x - 0.3, 0.4, 0.5, 0.55, 0.667) glasses. The concentration dependences of the spectra of inner Pb4f, Si2p, and Ols levels led to the conclusion that for low contents of PbO, lead is present in the glass in the form of modifying ions, whereas in high concentrations, it plays the role of glass former. Restructuring in the glass occurs for about 50% molar concentration of PbO. The Pb - O bond in the glass is more ionic than in PbO. With an increase in the PbO content in the glass, the Pb - O bond becomes closer to that of lead monoxide, i.e., is more covalent.     

17O MAS NMR study of 12-molybdophosphoric acid

¹⁷O MAS NMR spectra for¹⁷O enriched solid heteropoly acid H₃PMo₁₂O₄₀ are reported. The oxygen exchange between solid H₃PMo₁₂ ¹⁷O₄₀ and H₂ ¹⁶O vapor at 200–250°C is shown to be accompanied by fast mixing of terminal Mo=O and bridging Mo-O-Mo oxygens in the Keggin unit. The oxygen exchange in H₃PMo₁₂ ¹⁷O₄₀ is much faster than in H₃PW₁₂ ¹⁷O₄₀ in solution as well as in the gas phase.     

New acid catalyst comprising heteropoly acid on a mesoporous molecular sieve MCM-41

New solid acid catalysts, consisting of heteropoly acid (HPA) H₃PW₁₂O₄₀ (PW) supported on a mesoporous pure-silica molecular sieve MCM-41, have been prepared and characterized by nitrogen physisorption, X-ray diffraction, FT-IR, and³¹P magic angle spinning NMR. The PW/MCM-41 compositions with PW loadings from 10 to 50 wt% have 30 Å uniformly-sized mesopores. HPA retains the Keggin structure on the MCM-41 surface and forms finely dispersed HPA species. No HPA crystal phase is developed even at HPA loadings as high as 50 wt%. PW/MCM-41 exhibits higher catalytic activity than H₂SO₄ or bulk PW in liquid-phase alkylation of 4-t-butylphenol (TBP) by isobutene and styrene. In the alkylation of TBP by styrene, PW/MCM-41 shows a size selectivity compared to bulk PW and PW/SiO₂, providing higher yields of a 2-(1-phenylethyl)-4-t-butylphenol, at the expense of the more bulky 2,6-bis-(1-phenylethyl)-4-t-butylphenol. The PW/MCM-41 compositions, having strong acid sites and a regular mesoporous system, are promising catalysts for the acid-type conversion and formation of organic compounds of large molecular size.     

High-temperature thermoplastic strengthening of steels St3sp and 09G2S

Conclusions We worked out a regime of high-temperature thermoplastic treatment of steels St3sp and 09G2S consisting in austenization at 1020°C, strain (=200%, =5.7%) at 940°C with subsequent cooling at a rate >100°C/sec.As a result of such treatment the tensile strength of steel St3sp is increased to 1230 N/mm², of steel 09G2S to 960 N/mm², and the conventional yield strength to 1100 and 840 N/mm², respectively.N. É. Bauman Moscow State Technical University. All-Union Research Institute of Metallurgical Machinery Construction. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 7, pp. 18–19, July, 1991.     

Equation of state of the liquid alkali metals. I.

Experimental PVT data are given for sodium, rubidium, and cesium in the liquid phase. Procedures and measurement errors are discussed.Notation P pressure - V volume - T temperature - density - R solubility - D coefficient of diffusion - t time - L diffusion length - thermal expansion - C_p isobaric specific heat Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 35, No. 5, pp. 901–907, November, 1978.     

Rare Metal and Rare Earth Recovery from Silica Gel—Eudialyte Concentrate Leaching Product

Journal of Mining Science - The effect of various parameters (S:L ratio, duration, temperature and intensity of ultrasonic treatment) on recovery efficiency of zirconium and rare earth elements...