The complexation of linear chitosan with hydrogel of poly(acrylic acid) was studied in acetic acid solutions. It was found that the complexation is accompanied by contraction of hydrogel samples with formation of turbid layer on their surface. The dynamic changes of swelling ratio of poly(acrylic acid) hydrogel in course of the interaction with chitosan are interpreted from the diffusion theory point of view considering the properties of double electric layer on hydrogel-solution boundary. The FTIR spectroscopy method revealed the electrostatic mechanism of interaction between poly(acrylic acid) hydrogel and chitosan. The spectrum of polycomplex shows the bands, which are characteristic for both poly(acrylic acid) (1725, 1450, 1249 cm -1 ) and chitosan (1648, 1536, 1165, 1091, 1023 cm -1 ) confirming the sorption of the later polymer by hydrogel of poly(acrylic acid). The possibility of encapsulation of antibiotic levomycetin into polycomplex hydrogels as well as its release from the capsules has been studied. It was found that the maximal value of the drug released from the polycomplex capsule is achieved after the longer period in comparison with control experiment with its release from pure PAA hydrogel. It was shown that the interpolymer interactions between oppositely charged linear polymers and hydrogels could be successfully used for preparation of encapsulated forms of various physiologically active substances.
Conduction and superconductivity in quench condensed metallic films AIP Conf. Proc. 286, 96 (1992); 10.1063/1.44693 I n s i t u electrical conductivity and amorphouscrystalline transition in vacuumdeposited amorphous thin films of a Se5 0Te5 0 alloy An UHV deposition system for the production of amorphous transition metal alloy films by quench condensation from the vapor phase onto substrates held at liquid-helium temperature is described. The system can be operated with either of two helium cryostats which are designed for different in situ experiments. One of the cryostats incorporates a superconducting solenoid for superconducting critical field, Hall effect, and magnetoresistance measurements from 1.4 to 300 K in fields to 7 T. The other, which provides a larger working space, can be used for a variety of in situ experiments (a rapid survey of the properties of amorphous alloys as a function of concentration, thin-film heat capacity measurements, or superconducting tunneling experiments) between 1.4 and 300 K. Critical field and Hall coefficient measurements for amorphous Ti-V alloys and tunneling results for amorphous gallium films are presented to illustrate the system capabilities.
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