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The dissolution profiles of formulations based on mixtures of chitosan/alginate depend on the pH. It is possible to distinguish two processes: (a) a fast kinetic drug release up to 180 min, where the pH value changes from 1.17 to 2.21 and the drug released is controlled by the degree of polymerization and the quantity of chitosan in the formulation; (b) a low kinetic drug release between 210 and 480 min, where the pH value changes from 5.52 to 8.72 and the drug release from the matrix is controlled by the interpolymeric complex. In all formulations the order of release, according to Peppas's model in the range of fast kinetic drug release, was between 0.5 and 1.0. The mechanism of release was non-fickian diffusion, which corresponds to a coupling mechanism of diffusion and relaxation of the polymer.

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The Unit Operations Laboratory offers 2 courses in unit operations. One is a 2‐semester course for chemistry and food engineering students that is more demanding because it considers more unit operations and places more emphasis on solving exercises. The other is a 1‐semester course for chemistry and pharmacy students that considers fewer unit operations and is more descriptive. We have developed a web site with multimedia contents and interactive exercises, mainly for students with fewer abstract and mathematical learning styles who prefer visual, spatial, and hands‐on learning situations. For the development of multimedia elements, the more common unit operations that have greater learning difficulties related to the course audience were considered. For the course oriented to chemistry and food engineering students, the unit operations considered were size reduction, mixing of liquids, distillation, microfiltration, and solid‐liquid extraction. The evaluation of the site consisted in gathering the students' opinions but did not measure the impact of learning. The results showed that the students have a good opinion of the design of the web site and that the multimedia elements included are useful teaching tools.