Design of Liquid-Ring Vacuum Pump with Adjustable Degree of Internal Compression

Chemical and Petroleum Engineering - Liquid-ring vacuum pumps are used in oil recovery, in processing of plastics, in distillation processes, and other elsewhere. A major drawback of liquid-ring...     

Antioxidant Potential of Aqueous Dispersions of Fullerenes C60, C70, and Gd@C82

The antioxidant potential (capacity and activity) of aqueous fullerene dispersions (AFD) of non-functionalized C₆₀, C₇₀, and Gd@C₈₂ endofullerene (in micromolar concentration range) was estimated based on chemiluminescence measurements of the model of luminol and generation of organic radicals by 2,2′-azobis(2-amidinopropane) dihydrochloride (ABAP). The antioxidant capacity was estimated by the TRAP method, from the concentration of half-suppression, and from the suppression area in the initial period. All three approaches agree and show that the antioxidant capacity of AFDs increased in the order Gd@C₈₂ < C₇₀ < C₆₀. Mathematical modeling of the long-term kinetics data was used for antioxidant activity estimation. The effect of C₆₀ and C₇₀ is found to be quenching of the excited product of luminol with ABAP-generated radical and not an actual antioxidant effect; quenching constants differ insignificantly. Apart from quenching with a similar constant, the AFD of Gd@C₈₂ exhibits actual antioxidant action. The antioxidant activity in Gd@C₈₂ is 300-fold higher than quenching constants.     

Information terminological system for inorganic materials science (exemplified by concrete science)

Using concrete science as an example, we discuss priority issues in and principles and methodology of creating information terminological systems for inorganic materials science. The development of such systems builds on a typological approach, terminological field indexing methods, etc.     

Effects of Aqueous Dispersions of C60, C70 and Gd@C82 Fullerenes on Genes Involved in Oxidative Stress and Anti-Inflammatory Pathways

Background: Fullerenes and metallofullerenes can be considered promising nanopharmaceuticals themselves and as a basis for chemical modification. As reactive oxygen species homeostasis plays a vital role in cells, the study of their effect on genes involved in oxidative stress and anti-inflammatory responses are of particular importance. Methods: Human fetal lung fibroblasts were incubated with aqueous dispersions of C₆₀, C₇₀, and Gd@C₈₂ in concentrations of 5 nM and 1.5 µM for 1, 3, 24, and 72 h. Cell viability, intracellular ROS, NOX4, NFκB, PRAR-γ, NRF2, heme oxygenase 1, and NAD(P)H quinone dehydrogenase 1 expression have been studied. Results & conclusion: The aqueous dispersions of C₆₀, C₇₀, and Gd@C₈₂ fullerenes are active participants in reactive oxygen species (ROS) homeostasis. Low and high concentrations of aqueous fullerene dispersions (AFD) have similar effects. C₇₀ was the most inert substance, C₆₀ was the most active substance. All AFDs have both “prooxidant” and “antioxidant” effects but with a different balance. Gd@C₈₂ was a substance with more pronounced antioxidant and anti-inflammatory properties, while C₇₀ had more pronounced “prooxidant” properties.     

Tribological Studies of Lubricants

This paper describes an upgraded installation, a procedure, and results of lubricants testing with respect to use in the executive mechanisms of space vehicles.     

Preparation and properties of BaTiO<Subscript>3</Subscript>/porous oxide composites

Barium titanate has been synthesized in pores of oxide matrices using barium titanyl oxalate and barium titanyl peroxide (peroxotitanate) by a sol-gel process and by dispersing the precursors together with pyrogenic oxides in water. The composites were characterized by X-ray diffraction, differential thermal analysis, nitrogen adsorption measurements, transmission electron microscopy, dielectric spectroscopy, and photocatalytic activity measurements. The results demonstrate that the pore structure of the composites forms concurrently with their crystal structure. The composite produced using pyrogenic alumina has high dielectric permittivity.     

Ferromagnetism in diluted Pb1 ? x ? y Ge x Cr y Te magnetic semiconductors

Magnetic properties of Pb_{1 − x − y} Ge _x Cr _y Te alloys (x = 0.02–0.20, y = 0.01–0.08) were studied. It was detected that the magnetic susceptibility of alloys consists of two contributions: the paramagnetic Curie-Weiss part (the temperature region is T < 50 K) caused, probably, by the Cr³⁺ ion paramagnetism, and the high-temperature ferromagnetic part (T < 300 K). The dependences of the concentration of magnetic centers on the composition of the matrix were obtained from the paramagnetic and ferromagnetic contributions. It was shown that a decrease in the concentration of paramagnetic centers can be, at least qualitatively, explained by the transformation of the electronic structure as the germanium concentration increases. A phenomenological model was suggested, which explains the behavior of magnetic properties as the chromium content increases, and possible mechanisms of ferromagnetic ordering in studied alloys are discussed. Original Russian Text ? E.P. Skipetrov, M.G. Mikheev, F.A. Pakpour, L.A. Skipetrova, N.A. Pichugin, E.I. Slyn’ko, V.E. Slyn’ko, 2009, published in Fizika i Tekhnika Poluprovodnikov, 2009, Vol. 43, No. 3, pp. 316–323.