Inelastic processes in collisions of multicharged fast ions with atoms

We use the eikonal approximation to develop a general formula for the cross sections of inelastic collisions of multicharged fast ions (including relativistic ions) with atoms that is applicable within a broad range of collision energies, has the standard nonrelativistic limit, and becomes, in the ultrarelativistic case, the well-known result that follows from the exact solution of the Dirac equation. As an example we study the excitation and ionization of a hydrogenlike atom, the single and double excitation and ionization of a heliumlike atom, and multiple (up to the eighth order) ionization of the neon atom and (up to eighteenth order) ionization of the argon atom. We derive simple analytical expressions for the inelastic cross sections and establish recurrence relations linking the cross sections of ionization of different orders. Finally, we compare our results with the experimental data. Zh. éksp. Teor. Fiz. 114, 1646–1660 (November 1998)     

Isolation of phospholipase A2 from the venom of the green toadBufo viridis

Phospholipase A₂ has been isolated fromthe venom of he Central Asian green toad Bufo viridis in the electroophoretically homogeneous state for the first time by biospecific absorption chromatography. The affinity sorbent used was Affi-Gel 10 with covalently bound phosphatidylserine (PDS). The chemical inertness of the bound PDS to the hydrolytic action of phospholipase A2 and its high tendency to form biospecific complexes have been shown. Some biochemical characteristics of the enzyme isolated have been studied: influence of the pH and of the Ca²⁺ concentration and dependence of activity on substrate concentration.A. S. Sadykov Institute of Bioorganic Chemistry, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax 627071. Tashkent State University, fax 462472. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 105–109, January–February, 1994.     

Plant polysaccharides I. Polysaccharides ofLagochilus and their biological activity

Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 313–314, March–April, 1995. Original article submitted November 7, 1994.     

Wide-aperture cathodoluminescent light source based on an open discharge

The feasibility of an effective high-luminance light source based on an open discharge is considered. Experimental data for the light characteristics of different cathodoluminescent screens are presented. Phosphor coatings are excited by an electron beam initiated by a planar cathode-grid injector in an inert gas atmosphere. The feasibility of maintaining an open discharge using continuous or pulsed-periodic excitation of the gas medium in the light emitter is discussed. The use of the specular method to excite the phosphor coating of the screen makes it possible to achieve a higher luminance and a higher luminous efficacy in comparison with these characteristics for cathodophosphors. The design of the cathode-grid unit allows for a large surface area of the electron injector, making it promising for wide-aperture light sources.     

Dynamics of nanodefects on a loaded gold surface

The dynamics of defects with linear dimensions from ≈1 to ≈100 nm on a Au surface under load have been studied by means of tunnelling microscopy. It is found that the origin, growth, and resorption of the defects is caused by displacements of bands of material from 5 to 50 nm wide, parallel to the {111} slip planes. The defects can be separated into two groups: nonsteady-state defects, whose lifetime does not exceed 15 min, while the depth is ⩽20 nm, and quasi-steady-state defects, with a lifetime three orders of magnitude greater than the first. It is assumed that the nonsteady-state defects are formed when the ensemble of dislocations is being reconstructed, while the quasi-steady-state defects are formed at the instant of formation of dislocation substructures during the creep of the loaded metal. Fiz. Tverd. Tela (St. Petersburg) 40, 2180–2183 (December 1998)