Composite films based on an alicyclic polyimide and a natural mineral,montmorillonite

Specific features of preparing composites of an alicyclic polyimide with various forms of montmorillonite were studied. The kinetic parameters of the polyimide formation under the conditions of the onestep polycondensation in the presence of the modified mineral were determined, and some physicomechanical and thermal properties of the films were examined.     

Synthetic and natural polymers as drug carriers for tuberculosis treatment

Drug forms based polymer carriers of prolong action were created for toxicologic effect of drug to be reduced in spite of long treatment of diseases. In present work a number of synthesis and natural polymers have been studied as carriers of antituberculous drugs for controlled delivery application. Following as drugs as isoniazid and ethionamide were incorporated into polymeric matrix (segmented polyurethanes, polyvinyl alcohol) and chemically bound with the polymer chain by covalent or electrostatic forces (aldehyde- and carboxymethylderivatives of polysaccharides). Biodegradation of polymeric systems and the release of drugs were studied by various physico-chemical methods. It was shown that the drug release depends of method of the immobilization, type of the drug/polymer bonding, drug loading. The bacteriostatic activity of obtained systems was determined. The possibility of tuberculosis treatment was proved in experiments of animals.     

The Electrotechnical Complex of the KTM Tokamak Pulsed Power Supply System

The pulsed power supply equipment belongs to the basic technological systems intended for implementing the required scenarios of changing currents in magnetic coils. The accuracy of implementing these scenarios directly determines the possibility of attaining the plasma breakdown and the required ultimate plasma parameters. Given the uniqueness of each facility under construction in the world and the installed capacity of the electrotechnical equipment applied in the power supply configuration, one can state with confidence that the construction of similar power supply complexes and their control systems, the optimization of their electrotechnical parameters, and the subsequent accident-free operation are vital tasks in mastering controlled thermonuclear fusion technologies. This paper describes the pulsed power supply system of the KTM tokamak (Kazakhstan) designed for material testing, the digital control system for its power conversion equipment, electrotechnical solutions adopted in the design of the KTM tokamak pulsed power supply system, and findings of tests of some items of equipment and their components. The tests have demonstrated sufficient efficiency of the adopted electrotechnical solutions and the possibility of applying them to implement the pulsed power supply systems for small and medium sized tokamaks.     

Controlled Release of Farmazin from Thermosensitive Gels Based on Poly(N-vinylcaprolactam)

With the aim to prolong the effect of a wide-spectrum antimicrobial agent, Farmazin (tylosine tartrate), this drug was immobilized on a gel of N-vinylcaprolactam-sodium itaconate copolymer, which undergoes a phase transition on heating. The phase transition, accompanied by a change in volume, in aqueous solutions of the pure copolymer gel and that with the immobilized drug was studied.     

Polyurethanes as Carriers of Antitumorous Drugs

Drug delivery systems on a polyurethane base with various antitumorous drugs, such as cyclophosphane, thiophosphamide and vincristine, have been prepared. An in vitro technique was used to determine the release characteristics of the drugs into model biological media. It was shown the drug release occurs in accordance with first-order kinetics, as well a maximum degree for the drug loading were studied. The thermodynamic parameters of drug release has been determined. It was illustrated that the activation energies were 4.3, 3.9 and 3.2 kcal/mole for cyclophosphane, thiophosphamide and vincristine respectively, corresponding to a diffuse-controlled mechanism of release. © 1998 John Wiley & Sons, Ltd.