The synthesis and properties of homologous series of surfactants containing the pyrrolidinium head group with hydroxyethyl moiety

The surface activity, micelle formation, and solubilization ability towards hydrophobic compounds were estimated for the series of new cationic surfactants belonging to the type of 1-alkyl-1-(2-hydroxyethyl)pyrrolidinium bromides. The presence of 2-hydroxyethyl group in these surfactants leads to the twofold increase in their micelle-forming ability as compared to unsubstituted analogs. The critical micelle concentration for the investigated series of pyrrolidinium surfactants is lower at the same hydrophobicity than that for the analogs belonging to the alkylpyridinium, alkylimidazolium, and alkylmorpholinium types. The data acquired for the studied surfactants on their solubilization ability, antimicrobial activity, and hemolytic efficiency indicate their prospective applications to encapsulate hydrophobic biologically active molecules and as the promising bactericidal agents.

     

Enhanced macroscopic quantum tunneling in Bi2Sr2CaCu2O8 + delta intrinsic Josephson-junction stacks

We have investigated macroscopic quantum tunneling in Bi(2)Sr(2)CaCu(2)O(8 + delta) intrinsic Josephson junctions at millikelvin temperatures using microwave irradiation. Measurements show that the escape rate for uniformly switching stacks of Nu junctions is about Nu(2) times higher than that of a single junction having the same plasma frequency. We argue that this gigantic enhancement of the macroscopic quantum tunneling rate in stacks is boosted by current fluctuations which occur in the series array of junctions loaded by the impedance of the environment.     

Complexes of 1-hexadecyl-4-aza-1-azoniabicyclo[2.2.2]octane bromide with transition metal nitrates. Micelle-forming,solubilizing, and adsorption properties

Amphiphilic complexes of 1-hexadecyl-4-aza-1-azoniabicyclo[2.2.2]octane bromide (D-16) with nitrates of transition metals (La³⁺, Cu²⁺, Ni²⁺, and Co²⁺) have been synthesized and characterized. Absorption spectrophotometry in the UV, visible, and IR regions, as well as ¹Н NMR spectroscopy, have been employed to study their spectral properties in water and organic media. Adsorption properties and micelleforming and solubilizing abilities of the amphiphilic complexes have been investigated in aqueous solutions by the methods of tensiometry and conductometry, as well as by solubilization of a water-insoluble dye (Orange OT). The values of the critical micelle concentration, adsorption parameters at a water/air interface, and solubilization capacity S of complex micelles have been determined. It has been shown that the most pronounced decrease in the critical micelle concentration (as large as two to three times) and differences in the adsorption characteristics and the S values as compared with those of ligand D-16 are observed for complexes of copper and lanthanum. The S values for these complexes are 1.3?2.5 and 3?6.5 times higher than those for D-16 and cetyltrimethylammonium bromide, respectively.     

Identification of Petroleum Products in Environmental Samples Using Gas Chromatography and Gas Chromatography–Mass Spectrometry

Typical analytical features of petroleum products in environmental samples were considered. Among them are typical shapes of chromatograms; peaks of n-alkanes; the ratio between n-alkanes with even and odd numbers of carbon atoms; peaks of biomarkers (isoprenanes, steranes, triterpanes, etc.); the predominance of methyl- and alkyl-substituted mono-, bi-, and polynuclear aromatic hydrocarbons over unsubstituted aromatic hydrocarbons; and other features. These features altogether enable reliable conclusions about the petroleum origin of the identified pollutants to be made.     

Aggregation Capacity and Complexation Properties of a System Based on an Imidazole-Containing Amphiphile and Bovine Serum Albumin

A complex of physicochemical methods was used to study the aggregation characteristics of an imidazolium-containing amphiphile and its ability for complex formation with bovine serum albumin (BSA). Tensiometry showed that adding BSA to the surfactant decreases the aggregation threshold of the system by a factor of 50. Dynamic light scattering established, that the size of the surfactant–BSA complexes depends on the size of the polypeptide (6–10 nm) and is independent on the concentrations of the surfactant and BSA. The Stern?Volmer constants and surfactant?protein binding constants were calculated from fluorescence spectroscopy data.     

Radionuclide contamination of the LIRA faciliticies territory

Radiation situation at the LIRA site has been investigated. It served as a test site for 6 underground nuclear explosions. In comparison with background in the region the explosions caused a slight increase of the level of radionuclide contamination in the territory of the site. It was found that the release of ¹³⁷Xe and ⁹⁰Kr onto the surface is the main reason for formation of additional contamination with ¹³⁷Cs and ⁹⁰Sr. The peculiarities of the distribution and migration of the radionuclides in dependence on the relief and soil conditions are taken into consideration.     

Complex formation and self-association in the alkylated polyethyleneimine-calix[4]resorcinarene-chloroform system

Complex formation and self-association in the system alkylated polyethyleneimine-calix[4]resorcinarene-chloroform were studied by UV spectrophotometry, dilecometry, and light scattering. The constant of complex formation of polyethyleneimine with calixarene was found to depend on the hydrophobicity of the components of the system and presence of surfactants.