A study of the composition of polyacrylamide-polyaluminum chloride polymer-colloid complexes

The behavior of aqueous solutions of polymer-colloid complexes based on polyacrylamide (M ～ 5.2 × 10⁵) and colloid particles of polyaluminum chloride depending on the initial component ratio and the concentration of a low-molecular-mass electrolyte (NaCl) was studied by means of viscometry and turbidimetry. It was suggested that the composition of polymer-colloid complexes, ? (the number of colloid particles attached to one macromolecule), depends on the component ratio. At ? > 1, the polymer-colloid complexes take on the polyelectrolyte properties, namely, repulsion in the case of overlap of the diffuse layers of counterions of colloid particles bound to the polymer chain leads to unfolding of macromolecular coils. Correspondingly, as the concentration of a low-molecular-mass salt increases, the coil size diminishes and the solubility of the complex drops. At ? = 1, the concentration of low-molecular-mass salt has no effect on the solubility of the complex and the viscosity of its solution.     

Reaction of Hypoxanthine and Its Analogs with Acrylonitrile in Liquid Ammonia

Russian Journal of General Chemistry -     

Water-Soluble Non-Classical Benzene Mimetics

A new generation of saturated benzene mimetics, 2-oxabicyclo[2.1.1]hexanes, was developed. These compounds were designed as analogues of bicyclo[1.1.1]pentane with an improved water solubility. Crystallographic analysis of 2-oxabicyclo[2.1.1]hexanes revealed that they occupy a novel chemical space, but, at the same time, resemble the motif of meta-disubstituted benzenes.     

Solid-State Flexural–Vibrational Low-Frequency Magnetic Field Sensor Based on the Piezoelectric Effect

Technical Physics - Optimal geometrical and electrophysical parameters are calculated theoretically; the effective response of a solid-state hybrid...     

Polyethylenimine complexes with silver ions in aqueous solutions as precursors for synthesis of monodisperse silver iodide particles

The conditions of formation and composition of polyethylenimine complexes with silver ions in aqueous solutions are found. The complex is formed according to the model of a uniform distribution of ions throughout the macromolecule, and the composition of the complex may vary depending on pH of the medium. The size parameters are determined and the volume fractions of polyethylenimine macromolecular coils in solution are calculated. The synthesis of silver iodide particles is carried out under conditions where the silver ions are bound in the complex with polyethylenimine macromolecules and are distributed homogeneously over the volume of solution. The use of the polyethyleneimine complex with silver ions as a precursor of silver iodide allows the preparation of particles 1.2 nm in diameter with a narrow size distribution.     

Approximation by maps with nonnegative Jacobian

The problem of approximating continuous maps by smooth maps with nonnegative Jacobian is considered.     

Influence of cycloartanes from plants of the genusAstragalus and their synthetic analogs on the contractive function of the myocardium and the activity of Na,K-ATPase

An evaluation has been mde of the cardiotonic activities of cycloartane methylsteroids isolated from plants of the genusAstragalus and their synthetic analogs. It has been established that the compounds investigated exhibit a positive inotropic effect expressed to different degrees. The mechanism of the realization of the positive inotropic action of cycloartane glycosides differs from that of cardiosteroid drugs. Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 510–514, July–August, 1994.     

Charge transfer interactions between nucleic acid bases and strong acceptors

The regularities of the donor-acceptor interaction of nucleic acid bases and some of their derivatives with the strong acceptor 7,7,8,8-tetracyanoquinodimethane (TCNQ) in thin amorphous films at 77 K were studied using UV and visible spectroscopy. Purine and pyrimidine bases are shown to form charge transfer TCNQ complexes whose band energies hν_ct = I_p ? E_A ? (H* ? H⁰) are linearly dependent of the donor ionization potential I_p. Calculated differences between the interaction energies of uncharged molecules and ion radicals, ΔE ≈ 3.0 eV, are in good agreement with experimental variations of the complex dissociation energies in the ground and excited states, (H* ? H⁰) = 2.73 eV. Annealing of the films of complexes containing cytosine, 1-methylcytosine, uracil, and caffeine leads to ordering of their structure and the formation of ion radical salts.