The action of α-radiation on aqueous acid solutions

We investigated the action of polonium -radiation on a 0.8 N aqueous solution of sulfuric acid.It was established that over a wide range of dissolved polonium concentrations (0.1–12 mC/ml), the initial radiation-chemical hydrogen peroxide yield remains the same and equals 1.20 molecules per 100 ev of absorbed energy and that the hydrogen peroxide concentration tends toward a limit. The equilibrium limit of hydrogen peroxide concentration in 0.8 N sulfuric acid is 5–8·10¹⁸ molecules/ml.     

Ab initio calculations of the walls shear strength of carbon nanotubes

The dependence of the energy of interwall interaction in double-wall carbon nanotubes (DWNT) on the relative position of walls has been calculated using the density functional method. This dependence is used to evaluate forces that are necessary for the relative telescopic motion of walls and to calculate the shear strength of DWNT for the relative sliding of walls along the nanotube axis and for their relative rotation about this axis. The possibility of experimental verification of the obtained results is discussed.     

The use of titanium aluminides to form electric-spark coatings

Titanium aluminides (TiAl₃, TiAl, Ti₃Al) fabricated by powder metallurgy were used as alloying electrodes for the formation of electric-spark coatings. Intermetallic coatings were deposited on steel substrates in argon or nitrogen. The microstructure and composition of fabricated coatings were investigated by scanning electron microscopy, X-ray structural analysis, and electron probe microanalysis. It is established that initial Ti–Al intermetallic phases are present in fabricated coatings; however, the ratio between Ti and Al concentrations is shifted to aluminum compared with the stoichiometric one. When depositing titanium aluminide in the nitrogen medium, titanium nitride is additionally formed in surface layers. Thermal and tribotechnical tests showed that the Ti₃Al coating deposited in nitrogen possesses high wear resistance and heat resistance.     

The x-ray morphometric characteristics of the spine in persons 50 and older

To specify shape of the vertebra in relation to age and sex, the authors studied roentgenomorphometric evidence upon examination of the thoracic and lumbar spine in 600 patients over 50. Vertebral deformities were found in 45.1 and 44.5% of the examined males and females, respectively. Changes corresponding to vertebral body fracture were recorded in 12.3% of the males and 15.3% of the females. Age-related trends in the frequency of various defects have been analyzed. The frequency differed in males and females.     

Sensitivity of clonogenic cells of human ascitic ovarian cancer to antitumor agents

A soft agar colony assay using diffusion chamber technique in vivo for studying the sensitivity to chemotherapeutic agents of clonogenic tumor cells of primary ovarian carcinoma was used. The highest cytotoxic sensitivity on human clonogenic tumour cells was observed to cyclophosphamide and 5-fluorouracil. The sensitivity of human ovarian carcinoma to chemotherapeutic agents was dependent essentially on the presence of macrophage in cell culture.