Synthesis of Polyacrylamide Gels for Restricting the Water Inflow in Development of Oil Fields

Thermally stable hydrogels resistant to highly mineralized stratal water were synthesized from the nonionogenic polyacrylamide, paraform, resorcinol, sulfosalycilic acid, and Atren Fibre structuring additive. It was shown that the hydrogels are promising for development of gel screens in the borehole zone of oil-producing wells to restrict the water inflow and raise the oil recovery factor.     

Properties of solutions of water-soluble mixed esters of cellulose

The viscosity of solutions of water-soluble mixed esters of cellulose is determined. The dimensions of macromolecular globules and Huggins constants are calculated as functions of the nature of the substituted functional group on the water-soluble acetylcellulose. Tashkent Chemical Engineering Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 785–788, November–December, 1999.     

Electrophysical properties of composite films based on multiwalled carbon nanotubes under hydrostatic pressure

The effect hydrostatic pressure of up to 9 GPa has on the electrical behavior of polymer composites based on multiwalled carbon nanotubes (MWCNT) is investigated at room temperature. The ratio R _9GPa/R ₀ ≈ 7 for samples with resistance in the kilo-ohm range is higher than for samples in the ohm range. Pressure-induced MWCNT features at P ≈ 1.5 GPa are associated with the deformation of the circular form of nanotube walls, in agreement with theoretical predictions. Measurements of direct and reverse resistance and current voltage characteristics under pressure demonstrate the reversibility of electrophysical properties, which could find practical application in creating pressure sensors.     

Langmuir–Blodgett Films of Fatty Acid Salts of Bi- and Trivalent Metals: Y, Ba, and Cu Stearates

Dependences of the composition and properties of the monolayers and Langmuir–Blodgett films of yttrium, barium, and copper stearates on the conditions of their formation were studied by FTIR spectroscopy, X-ray photoelectron spectroscopy, and quartz crystal microbalance technique. The identity of film compositions on the surfaces of liquid and solid substrates was established. It was shown that, in the case of copper and yttrium, the Langmuir–Blodgett films are formed from corresponding basic salts of stearic acid at high subphase pH values. The conditions of the preparation of high-quality Langmuir–Blodgett films from yttrium, barium, and copper stearates are determined.     

Monolayers and Langmuir-Blodgett films of crown-substituted phthalocyanines

Tetra-15-crown-5-phthalocyanine ligand and its ruthenium complex with axial CO and MeOH groups were synthesized. The properties of their monolayers and Langmuir-Blodgett films were studied. In the case of the ligand, monolayer films of molecular associates are formed. The compatibility of the ligand and stearic acid in a mixed binary monolayer was established. Stearic acid improves the ligand distribution over the water surface and results in the formation of monolayer associates immobilized in its matrix. The condensation effect of Na⁺ cations on the mixed monolayers was found. The ruthenium complex (R₄Pc)Ru(MeOH)(CO) forms stable true monolayers. The macrocycle planes in stacking are inclined relatively to the normal to the subphase surface by an angle of 25°. The Langmuir-Blodgett films of the complex were established to have redox peaks. A high electrochemical stability of the Langmuir-Blodgett films and a high electroactivity of phthalocyanine rings were demonstrated. It was shown by impedance spectroscopy that the binding of Na⁺ and K⁺ ions by Langmuir-Blodgett films of the (R₄Pc)Ru(MeOH)(CO) complex results in an increase in the impedance values in a region of medium frequencies by three and five times, respectively.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2426–2435, November, 2004.     

Kinetics of Complexation in the Monolayers of Amphiphilic Dicetylcyclene on the Surface of Aqueous Copper(II) Chloride Solutions

The kinetics of complexation in monolayers of dicetycyclene at the surface of aqueous copper(II) chloride solutions was studied. It was shown that the changes in the phase state of monolayer related to the conformational transitions of macrocycle are responsible for the differences in the rate and binding mechanism of copper ions. It was concluded that the sterically more advantageous (for the coordination with the metal ion) conformation of macrocyclic polyamine is ensured in a monolayer. In addition, it was established that the rate and mechanism of complexation in such monolayers greatly depend on the degree of protonation of ligands, the latter being dependent on the subphase pH. It was also demonstrated that an increase in subphase pH to 7 and higher results in an almost total suppression of metal ion binding due to strong conformational distortion of dicetylcyclene macrocycles in a monolayer and the hydrogen bonding between macrocycles.     

Effect of phasons and magnetic fields on the electronic spectrum of a three-dimensional quasicrystal

The effect of phasons and magnetic fields on the electronic spectrum of an icosahedral quasicrystal is investigated in the tight-binding approximation. Phasons smooth the singular spectrum and produce a greater delocalization of the critical wave functions. A magnetic field shifts the limits of the spectrum, smooths the spectrum, lifts the degeneracy, and also delocalizes the wave functions. Pis’ma Zh. éksp. Teor. Fiz. 69, No. 9, 659–661 (10 May 1999)     

Artificial Iono‐ and Photosensitive Membranes Based on an Amphiphilic Aza‐Crown‐Substituted Hemicyanine

Artificial iono‐ and photosensitive membranes based on an amphiphilic aza‐crown‐substituted hemicyanine are assembled on liquid and solid supports and their aggregation behaviour, which is influenced by the binding of metal cations and surface density, is studied. The photoinduced charge‐transfer properties of an analogous non‐amphiphilic hemicyanine in solution are also demonstrated. An asymmetric sandwich dimer model is proposed and existence of such dimers in solution is evidenced by transient absorption and fluorescence anisotropy experiments. Changes in absorption and emission spectra, as well as compression isotherms of the amphiphile observed in the presence of cations, are discussed in terms of 2D molecular reorganisation. Surface‐pressure‐controlled reversible excimer formation at the air–water interphase and excimer‐type emission of Langmuir–Blodgett films in the presence of cations are demonstrated and are discussed on the basis of fibre‐optic fluorimetry and fluorescence microscopy results.     

Pressure and temperature dependences in p-ZnAs2 at high pressures

Kinetic effects in p-ZnAs₂ were measured at hydrostatic (P ≤ 9 GPa) and quasi-hydrostatic (to P ≤ 50 GPa) pressures on pressure buildup and depressurization. A conclusion on the occurrence of two phase transitions was made: I–II at P = 9–15 GPa and II-III at P = 30–35 GPa. Based on the temperature dependences of electrical resistance, it was shown that the conductivity is determined by activation mechanisms in a temperature range of 250–400 K; in this case, the activation energy changed with temperature and pressure. The pressure dependences of the activation energy and the coefficient R ₀, which characterizes the mobility, concentration, and effective mass of carriers, were calculated.