Alignment control of two-mirror telescopes using a system of annular computer-generated holograms

This paper presents some results obtained while examining the problem of controlling the alignment of two-mirror Cassegrain and Ritchey-Chretien telescopes. The alignment control uses a system of two coaxially mounted annular computer-generated holograms as optical compensators and sample optical elements.     

Gas release from an E125 zirconium alloy under hydrogenation and deformation conditions

The degassing from a hydrogen-saturated E125 zirconium alloy is studied as a function of its deformation. Zirconium alloy samples are subjected to tension at a relative elongation of 2.5, 5, and 10%. Undeformed and deformed samples were saturated with hydrogen by a galvanic method at a current density of 0.5 A/cm²; that is, they are hydrogen saturated and then deformed. As a result, the defects at which hydrogen is trapped in zirconium are identified. The quantity of hydrogen trapped by defects depends on the strain and the sequence of deformation and hydrogen saturation. This is a technical result of the investigations, which can be used to find optimum operation conditions for hydrogen-saturated zirconium articles.     

Methodological approaches to conducting pilot and proof tests on reverse-osmosis systems: Results of comparative studies

When designing large-scale water-treatment plants based on reverse-osmosis systems, it is proposed to conduct experimental-industrial or pilot tests for validated simulation of the operation of the equipment. It is shown that such tests allow establishing efficient operating conditions and characteristics of the plant under design. It is proposed to conduct pilot tests of the reverse-osmosis systems on pilot membrane plants (PMPs) and test membrane plants (TMPs). The results of a comparative experimental study of pilot and test membrane plants are exemplified by simulating the operating parameters of the membrane elements of an industrial plant. It is concluded that the reliability of the data obtained on the TMP may not be sufficient to design industrial water-treatment plants, while the PMPs are capable of providing reliable data that can be used for full-scale simulation of the operation of industrial reverse-osmosis systems. The test membrane plants allow simulation of the operating conditions of individual industrial plant systems; therefore, potential areas of their application are shown. A method for numerical calculation and experimental determination of the true selectivity and the salt passage are proposed. An expression has been derived that describes the functional dependence between the observed and true salt passage. The results of the experiments conducted on a test membrane plant to determine the true value of the salt passage of a reverse-osmosis membrane are exemplified by magnesium sulfate solution at different initial operating parameters. It is shown that the initial content of a particular solution component has a significant effect on the change in the true salt passage of the membrane.     

A study of the adsorption of silver nanoparticles by high-performance liquid chromatography

The method of high-performance liquid chromatography has been used to study the adsorption of stable silver nanoparticles, which were obtained by radiation-chemical synthesis in reverse micellar solutions of H₂O + Ag⁺/Aerosol OT/isooctane composition. Adsorption was conducted on polar and nonpolar sorbents. It has been determined that almost all nanoparticles are retained on nonpolar sorbent C18; however, their binding is not strong. After accumulation of a particular amount of nanoparticles, they leave a column with effluent. It has been shown that the adsorption and optical properties of silver nanoparticles almost do not change after the adsorption-desorption cycle on C18. It has been determined that, on polar silica gel, the adsorption of silver nanoparticles proceeds less intensely (fewer than half of the particles move to the near-surface layer of the sorbent; however, their interaction with surface is very strong and they were not desorbed. For nanoparticles and the molecules of the micelle-forming agent Aerosol OT, adsorption isotherms have been plotted. Based on the obtained results, possible mechanisms of adsorption of nanoparticles on the surface of polar and nonpolar sorbents have been considered.     

Androstenedione conversion in human peripheral blood lymphocytes

Indigenous Indian groups comprise approximately 20% of Ecuador's population, the third largest percentage in all of Central or South America, yet immunogenetic data on these groups are lacking in the literature. In the course of population migration studies, sera collected from 65 Ecuadorians living in the northern province of Esmeraldas were typed for six GM and two KM markers. The study population consisted of 47 Cayapa Indians and 18 blacks of African origin, descendants of slaves imported into the area during the seventeenth century. The Cayapa demonstrated three GM phenotypes, two of which are common to other South American Indian tribes. The frequency of KM1 positive Cayapa Indians (63%) is similar to other South American Indian tribes, but is significantly greater than the Huaorani of eastern Ecuador (2%), the only other Ecuadorian Indian group for whom limited immunoglobulin allotype data are available (chi 2 = 35.8, P < 0.0001).