Effect of the properties of the water sorbent on the heat generation in the Fe-C-NaCl-H<Subscript>2</Subscript>O-O<Subscript>2</Subscript> system

The water adsorption and retention behaviors of vermiculite, silica gel, activated carbon, and a zeolite are analyzed in relation to their pore structures, and their effects on the dynamics of heat generation in Fe-C-NaCl-H₂O-O₂-water sorbent systems are investigated.     

Composition and structure of coatings based on rare-earth zirconates

Coatings based on lanthanum, neodymium, samarium, and gadolinium zirconates have been grown by atmospheric plasma spraying of powders, and their composition and structure have been investigated by scanning electron microscopy, chemical analysis, and X-ray diffraction. The results demonstrate that the chemical composition of the coatings differs from the compositions of the powders they were prepared from. During plasma spraying of Ln₂Zr₂O₇-based powders, the rare-earth oxide vaporizes more rapidly than zirconia. The difference in composition between the powders and coatings decreases as the atomic number of the rare earths increases in going from La to Gd. We have studied the processes that take place in the coatings during heat treatment at a temperature of 1250°C. It has been shown that the major phase in the La₂Zr₂O₇-, Nd₂Zr₂O₇-, and Sm₂Zr₂O₇-based coatings undergoes a defect fluorite–pyrochlore structural phase transition. The La₂Zr₂O₇-based coatings have been found to contain ～5 wt % t-ZrO₂ in addition to the major phase. The Gd₂Zr₂O₇-based coating retained a defect fluorite structure.     

Comparative Testing of One-Coat Enamels for Pipes

Comparative testing of industrially produced enamels and synthesized fluorine-free one-coat enamels was carried out. It was established that fluorine-free enamels of new compositions in certain properties (firing interval, chemical resistance, impact strength, etc.) exceed the existent analogs. The enamels are environmentally safe, have been subjected to extensive industrial testing, and have been accepted for production at various companies manufacturing steel pipes with enameled inner surfaces.     

Variants of Electrochemical Processing of Rhenium-Containing High-Temperature Alloy

In this paper we present the results of electrochemically processing the high-temperature HRA32-VI alloy in acid electrolytes in various electrolysis regimes. The optimal parameters of the electrochemical process for various current programs are determined. The dependence of the influence of the parameters of the current programs on the dissolution rate of the HRA32-VI alloy, the composition of the processed products, and the granulometric size of the cathodic precipitates and anode slimes is determined. Based on the results, we propose the principal technological scheme of HRA32-VI alloy processing.

     

Recovery of valuable components from basalt waste by sintering it with sodium carbonate

The sintering of basalt waste with sodium carbonate at 1000–1200°C followed by leaching of the sinter with water, a NaOH solution, or hydrochloric acid is reported. The most effective leaching agent is hydrochloric acid, with which all of the valuable components of basalt pass into solution and silicon can be selectively separated as silicic acid.     

Choledocholithiasis after cholecystectomy

Concrements were found in the ducts of 172 patients subjected to secondary surgical interventions on bile ducts. The detailed analysis of the data failed to answer the question whether the stones could be formed immediately in the ducts without such conditions as a mechanical obstacle for the outflow of bile, the presence of foreign bodies and a big stump of the cystic duct. Such a formation of stones can take place in very few cases. The authors have shown that control cholangiography and especially choledochoscopy can reduce the danger to leave the stones in the ducts, but does not eliminate the danger completely. Nevertheless they think that now it is possible to lessen the indications for biliodigestive anastomoses in choledocholithiasis since the retained stones can be revealed within the first days after surgery and, as a rule, removed with instruments or by other methods using the drainage left in the ducts.     

Preparation of ceria nanoparticles

Ceria nanoparticles (D = 2.4?6.9 nm) with the fluorite structure have been prepared via oxidative precipitation of cerium from a solution of a rare-earth chloride mixture, followed by acid washing.