No abstract

Experimental data on semiconducting organic substances are usually processed by use of the two-constant equation, σ(T) = σ0exp(−E / 2kT). Evidence from a number of cases now indicates that σ0 is dependent on E, when the equation is applied to certain single substances where E varies with preparation. A three-constant equation of the following form applies: σ(T) = σ0′ exp(E / 2kT0) exp(−E / 2kT) where T0 is a new constant, the “characteristic temperature” of the substance. A method of evaluating σ0′ and T0 is to vary the activation energy for semiconduction by any of at least three processes: (1) hydration of the crystals; (2) formation of weak donor–acceptor complexes; (3) using different cis–trans isomers of the substance when possible. One method of evaluating the constants is to plot logσ0vs E. The slope of this line yields (2kT0)−1, and the intercept yields σ0′. Other methods are possible and yield consistent results. These methods are demonstrated for the substances oxidized cholesterol, retinal, and nucleic acids. The implication of these results is that the Meyer–Neldel rule for compound inorganic semiconductors is valid for organic semiconductors as well. No reasonable theoretical explanation has yet been proposed to account for this rule.

No abstract

Women are very much susceptible for acquired immunodeficiency syndrome (AIDS) and other sexually transmitted diseases (STDs), mainly due to unprotected heterosexual vaginal intercourse and for some other social and economical disadvantages. Our aim was to formulate and optimize vaginal film of abacavir, a potent nucleoside reverse transcriptase inhibitor, for the treatment of AIDS and HIV. Abacavir films were prepared by solvent evaporation method using sodium alginate (Na-alginate) as the main polymer, Hydroxypropyl Methylcellulose E 15 (HPMC E 15) as the copolymer and glycerol as a humectant. Abacavir sulphate (ABC) was used here as a drug. Films were optimized for various physicochemical parameters such as tensile strength, % elongation at break, swelling capacity, drug content (mg/cm(2)), thickness, folding endurance, bioadhesion, pH, moisture content and SEM. Drug polymer interaction was studied by FTIR Spectra. The drug release study was accomplished in dissolution apparatus. In vivo study was also carried out. This newly formed film was one kind of sustain release type and can be considered as a novel drug carrier system for the treatment of AIDS and other STDs. It was suitable for local as well as systemic effect. The films showed good physicochemical property with good aesthetic appeal.

No abstract