The <Emphasis Type="Italic">A</Emphasis>-integral and its application in the study of P. L. Ul’yanov and other matematicians

In this paper we consider the A-integral and its application in the theory of trigonometric series.     

Metallomicellar Complex of 1-Hexadecyl-4-aza-1-azoniabicyclo-[2.2.2]octane Bromide with Copper Dibromide for Solubilization of Nitrofurantoin

Associates of amphiphilic 1-hexadecyl-4-aza-1-azoniabicyclo[2.2.2]octane bromide–copper dibromide complex solubilize nitrofurantoin (furadonin). The solubilizing capacity of premicellar aggregates with respect to nitrofurantoin is 15 times higher than that of micelles and is considerably higher (by a factor of 5–16) than the solubilizing effect of micellar solutions of the complex, ligand, and conventional cationic surfactants with respect to Orange OT.     

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.

     

Amphiphilic Compounds Containing a Carbamate Fragment: Synthesis,Aggregation, and Solubilizing Effect

A new cationic surfactant containing a butylcarbamate fragment as the head group and hexadecyl radical as hydrophobic component has been synthesized and characterized. Its aggregation paremeters have been determined by tensiometry, conductometry, and dynamic light scattering, and its solubilizing capacity for naphthalene and anthracene has been estimated.     

Catalytic activity of supramolecular systems on the basis of alkylated polyethylenimines,cationic surfactats,and calix[4]arenes

By means of the dielcometric titration and the dynamic light scattering, the association in the systems based on the alkylated polyethylenimines, hydroxyalkyl cationic surfactants, and calix[4]arenes in chloroform was studied. By means of the UV spectrophotometry the catalytic effect of the aggregates formed on the phosphorylation of polyethylenimines was established. Catalytic effect of the system depends on the structure of surfactants and calixarenes, and also on the relative content of the solution components.     

On the properties of orthorecursive expansions with respect to subspaces

In a Hilbert space, for orthorecursive expansions with respect to closed subspaces, we establish a criterion for expansions of elements of a certain finite-dimensional subspace with respect to a finite sequence of subspaces to coincide with the expanded elements. This implies a criterion for an element to be equal to its orthorecursive expansion with respect to a finite sequence of subspaces. We also obtain a number of results related to the best approximations of elements by partial sums of their orthorecursive expansions with respect to a sequence of finite-dimensional subspaces.     

Supramolecular Systems Based on Novel Mono‐ and Dicationic Pyrimidinic Amphiphiles and Oligonucleotides: A Self‐Organization and Complexation Study

Novel mono‐ and dicationic pyrimidinic surfactants are synthesized and their aggregation behavior is studied by methods of tensiometry and nuclear magnetic resonance (NMR) self‐diffusion. To estimate their potentiality as gene delivery agents, the complexation with oligonucleotides (ONus) is explored by dynamic light scattering (DLS) and zeta‐potential titration methods and ethidium bromide exclusion experiments. Bola‐type pyrimidinic amphiphile (BPM) demonstrates rather a weak affinity to ONus. Although it induces mixed associations with ONus, only slight charge compensation changes occur at a large excess of bola, with no recharging reached. Similarly, the ethydium bromide exclusion study reveals a slow increase in the binding capacity toward an ONu with an increment in BPM concentration. The monocationic pyrimidinic surfactant (MPM) and its gemini analogue (GPM‐1) are ranked as intermediates in both their aggregative activity and complexing properties toward ONus. They both form mixed associates with ONus well below the critical micelle concentrations (cmcs) of 2 and 15 mM respectively. However, GPM‐1 has a much lower isoelectric point at the molar ratio surfactant/ONu r～1 compared to r～3 for MPM. This probably indicates a larger electrostatic contribution to the ONu complexation in the case of GPM‐1. The most hydrophobic pyrimidinic surfactant (GPM‐2), bearing three alkyl tails, demonstrates enhanced aggregative activity and binding capacity toward ONus as compared to former pyrimidinic surfactants. Due to effective aggregative (low cmc of 0.04 mM ) plus binding properties (fraction of bound ONu β=0.76 at r=2.5), GPM‐2 may be ranked as a promising agent for wider biological applications.     

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.