Preparation and properties of heavy-metal halide glasses

We have studied the effect of In³⁺, Pb²⁺, Gd³⁺, and Cl (heavier ions) substitutions for Al³⁺, Ba²⁺, La³⁺, and F^? on the crystallization stability and UV/IR optical properties of HBLAN fluorohafnatc glasses (HfF₄-BaF₂-LaF₃-AlF₃-NaF system). We obtained stable glasses containing InF₃ and BaCl₂ instead of AlF₃ and BaF₂, respectively, and offering increased IR transmission. The presence of CCl₄ in the process atmosphere and the removal of oxygen-containing impurities via directional solidification are shown to have an advantageous effect on the optical quality of the glasses. The fluoride-chloride glasses are capable of accommodating about 1.5 times higher levels of rare-earth activators in comparison with their fluoride analogs.     

Trends in registered psychiatric morbidity and forecasting psychotropic drug needs in Bulgarian hospitals

Registered psychiatric morbidity in Bulgaria as a whole and particularly in Plovdiv, the second largest region of the country, was assessed. Three aspects of psychotropic drug usage were analysed, namely, changes in registered psychotropic drugs, the prescribed daily dose (PDD) values for 2 years, and the preferred therapeutic schemes, and drug usage and needs in a psychiatric hospital with 365 beds. This was done by time series analysis for evaluation of psychiatric morbidity and drug consumption data, calculation of PDD for psychotropic medicines, and, based on a modification of the World Health Organization's morbidity method, assessment and prediction of drug use and needs in Plovdiv hospital. The results indicated that the registered morbidity had increased by 4% over the period 1989-93 to 2,427 psychiatric patients per 100,000 people. The increased consumption of especially benzodiazepines and sedative medicines was analyzed. Diazepam was prescribed the most often (91.1%), followed by levomepromazine (86.4%), haloperidol (82.7%), etc. Future drug consumption in Plovdiv hospital is expected to decrease because therapeutic practice in hospitals has been revised and improved on the basis of the World Health Organization's recommendations.     

Contribution of K. A. Andrianov to the development of heat-resistant adhesives

Listed are the grades of heat-resistant adhesives developed under the Andrianov’s scientific guidance at the All-Russia Institute of Aviation Materials on the basis of organosilicon polymers.     

Reconstruction of radiation situation at Chernobyl NPP service area on the basis of γ-ray spectrometric analysis of soil samples and published data

Reconstruction of the radiation situation in areas subjected to nuclear accidents was done with an example of the Chernobyl accident (1986) on the basis of the radionuclidic composition of soil samples. The radionuclidic composition of γ-emitters was determined 19 years after the accident in a pulverescent sandstone sample collected in July 1986 at a distance of 1.5 km from the 4th block. Using reference data and data from original papers, reconstruction of the radionuclidic composition of the sample is done on the first ten days after the accident, and possible variations of the γ-radiation dose rate were determined within the framework of the thin film model. Based on the results obtained, variations of the absorbed dose of γ-radiation in 10 days are estimated, which is necessary for making urgent decisions in the initial period after the accident. The results are well consistent with the published data on the dose rates, validating the decision on evacuation of the people from Pripyat town and from the 30-km exclusion zone.     

An efficient implementation of certain iterative refinement preconditioners

Preconditioned iterative methods of conjugate gradient type for solving elliptic and parabolic problems discretized on grids wth local refinement are considered. The sparsity pattern of the residuals computed throughout the iterative process is investigated. It turns out that they are nonzero only near the interface nodes between the coarse-and fine-grids. This observation is used to formulate the preconditioned CG, and when the matrix is not symmetric as in the parabolic case—the generalized CG and GMRES methods, thus substantially saving storage and computation.     

Increasing the corrosion resistance of equipment due to the use of film-forming amines

Results of a study of tube specimens cut from hot-water boilers show that film-forming octadecyl amine (ODA) used in the process of preservation removes deposition from the surface of the metal. An ODA film is preserved on the surface after repeated washing of the latter with hot water. The concentration of chlorides at the surface of the metal after treatment with ODA is lower than before the treatment. __________ Translated from élektricheskie Stantsii, No. 11, November 2005, pp. 15–18.     

Effect of Dilution and Porosity on Self-Propagating High-Temperature Synthesis of Silicon Nitride

Self-propagating high-temperature synthesis is a very easy and low-cost method to synthesize Si₃N₄. The nitriding of silicon powder takes place in a self-sustained regime under high pressures of nitrogen with dilution of silicon by Si₃N₄. In this work effects of dilution and green-mixture porosity on combustion velocity and phase content of reaction products are studied. Results are compared with previous work of other authors and different behaviors are found. An explanation of these behaviors is given.     

Effect of prolonged high-temperature loading on the structure of the KhN65VMTYu alloy

A complex analysis of changes in the structure and in the phase composition arising as a result of both a prolonged operation of articles made of the alloy KhN65VMTYu (EI893) and after conducting imitation tests of model samples. The tests for long-term strength using samples cut out from the body of a large-dimension turbine blade which was exploited for 63 622 h showed that the blade preserved a significant residual reserve of service life (at 750°C and 250 MPa, the time to failure is 4243.5 h).     

Coal reserves of Republic of Sakha (Yakutia) and principal lines of their use

The Republic of Sakha (Yakutia) has the largest reserves of lignites and coals in the Far East owing to three coal basins—Southern Yakutia, Lena, and Zyryanskii—in the republican territory and the eastern part of the Tunguska basin. Main deposits, their resources, clay type composition, and lines of use are discussed.