Solubility of UF4, ThF4, and CeF3 in the NaF-ZrF4 melt

The solubility of UF₄, ThF₄, and CeF₃ in a fluoride melt 52 mol % NaF-48 mol % ZrF₄ in the temperature range 550–750°C was studied. The solubility of the fluorides in the melt increases with temperature. At 600°C and higher temperatures, the solubility decreases in the order UF₄ > ThF₄ > CeF₃. The temperature dependences of the solubility of UF₄, ThF₄, and CeF₃ in the NaF-ZrF₄ system are satisfactorily described by a linear equation.     

Prospects of further improvement of electric-discharge elastic-oscillation generators for treatment of melts in a ladle

On the basis of the functional analysis of the physicotechnical factors that have an effect on the load parameters of melts in a ladle under electrohydropulse treatment, recommendations on the further improvement of electric-discharge elastic-oscillation generators are given.     

On the Possibility of Retaining the Microporous Structure of the LSX Zeolite During Ion Exchage of K+,Na+ → $${\text{NH}}_{4}^{ + }$$

Protection of Metals and Physical Chemistry of Surfaces - By means of elemental and X-ray powder diffraction analysis, N2 adsorption at –196°C and CO2 adsorption at 0°C the textural...     

Cyclic Tests of Stress-corrosion Cracks in Steel Gas Pipelines with No Corrosive Fluid

Stress-corrosion defects in the output pipeline of a compressor station are subjected to metallographic analysis and mechanical tests. The pipeline consists of pipe imported in the 1980s. Diagnostic data obtained in nondestructive monitoring of such pipelines are analyzed, and the effectiveness of various diagnostic methods in detecting stress-corrosion defects in large-diameter pipe is assessed. The grade of steel in the pipeline is identified. The cracks are identified by type and morphology, and their development is determined. Nonmetallic sulfide inclusions have no influence on pipeline failure in the stress-corrosion conditions considered. The sulfur content in the corrosion products is no more than the sulfur content in the metallic sample. In some samples, the sulfur content may be decreased except for local sections with nonmetallic sulfide inclusions. Electron-microscope images show that such nonmetallic inclusions do not promote failure. The results of cyclic tests of cracked samples cut from the pipeline are presented. The test conditions are selected in accordance with recent operating conditions of the compressor station. According to the results, pipe with defects at the initial stage of development exhibits considerable durability in the tests. In fact, the cracked samples withstand (1.6–7.5) × 10⁶ cycles under transverse cyclic flexure in a single plane, in the absence of corrosive fluid. In practice, the number of such cycles is no more than 120–200 per year, in normal pipeline operation. Hence, a pipeline with stress-corrosion defects in their initial stage of development will last a long time if its metal wall is protected from the action of corrosive fluid.     

Influence of Lead Melts on the Embrittlement of Chromium Steels of Ferritic and Austenitic Classes

Materials Science - We study the influence of liquid-metal media of lead and the eutectic lead–bismuth mixture on the mechanical properties of chromium and chromium–nickel steels of...     

Stiffness of Monolithic Reinforced-Concrete Slab Structures

Materials Science - It is shown that the numerical analyses of slab reinforced concrete structures are, as a rule, based on the classical theory of bending of elastic plates. According to the...     

Influence of the quality of the heterointerface on the cyclotron resonance spectra of InAs/(AlGa)Sb heterostructures

Cyclotron resonance is measured in solitary type-II InAs-AlGaSb quantum wells grown by molecular-beam epitaxy under various growth conditions. Quantum oscillations observed in the cyclotron resonance spectra in InAs-GaSb samples are attributed to scattering by a short-range potential due to roughness of the heterointerface. A new method based on measurement of the cyclotron resonance spectra is proposed for assessing the quality of the heterointerface. Fiz. Tekh. Poluprovodn. 31, 1246–1248 (October 1997)     

The nootropic correction of disorders in learning and memory processes induced by extreme exposures

Experiments on rats demonstrated that the low-intensity electromagnetic field (12.6 cm, 2375 MHz, power density 1 mW/cm2), motion sickness, and electroconvulsive shock provoked the retrograde amnesia in the passive avoidance test. The oxyracetam (100 mg/kg, i.p.), aniracetam (50 mg/kg, i.p.), nooglutil (50 mg/kg, i.p.), meclofenoxate (50 mg/kg, i.p.), pyracetam (200 mg/kg, i.p.), and GABA (200 mg/kg, i.p) prevented the memory-impairing effect of all these extreme factors. On the contrary, the N-acetylglycinamide, semax, and other nootropic drugs were effective only under one or two extreme conditions.     

In vivo characterization of cytotoxic intracellular edema by multicomponent analysis of transverse magnetization decay curves

The precise measurement of low numbers of leukocyte below 0.1 WBC/microliter in filtered red cell or platelet suspensions meet both aims: to check the compliance with previously determined requirements and to evaluate the performances of novel filtering material (5 log depletion or more), justified by more and more important clinical use. The reliability of results, obtained with the chosen method, is ensured by applying of validation protocol, including training of technologist, assessment of the analytical range and the detection limit, assessment of precision and accuracy. The flow cytometry (FC) and Nageotte Chamber (NC) method are the both techniques which are currently used in routine Quality Control (QC) and validated by multicenter studies. Recent developments are made for increasing the sensibility of these counting methods, thanks to higher concentration or volume of the sample to be analysed. Among the experimental techniques, requiring more advances before implementing in QC program, quantitative PCR must become essential as reference method for evaluating the efficiency of filtration, in the future.     

Genetic analysis of delta helD and delta uvrD mutations in combination with other genes in the RecF recombination pathway in Escherichia coli: suppression of a ruvB mutation by a uvrD deletion

Helicase II (uvrD gene product) and helicase IV (helD gene product) have been shown previously to be involved in the RecF pathway of recombination. To better understand the role of these two proteins in homologous recombination in the RecF pathway [recBCsbcB(C) background, we investigated the interactions between helD, uvrD and the following RecF pathway genes: recF, recO, recN and ruvAB. We observed synergistic interactions between uvrD ant the recF, recN, recO and recG genes in both conjugational recombination and the repair of methylmethane sulfonate (MMS)-induced DNA damage. No synergistic interactions were detected between helD and the recF, recO and regN genes when conjugational recombination was analyzed. We did, however, detect synergistic interactions between helD and recF/recO in recombinational repair. Surprisingly, the uvrD deletion completely suppressed the phenotype of a ruvB mutation in a recBCsbcB(C) background. Both conjugational recombination efficiency and MMS-damaged DNA repair proficiency returned to wild-type levels in the deltauvrDruvB9 double mutant. Suppression of the effects of the ruvB mutation by a uvrD deletion was dependent on the recG and recN genes and not dependent on the recF/O/R genes. These data are discussed in the context of two "RecF" homologous recombination pathways operating in a recBCsbcB(C) strain background.