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The development of nanomaterials with improved functional characteristics is a priority because of their applicability in medicine. Therefore, in this study, chitosan nanofiber membranes were electrospun with polyvinyl alcohol supplemented with carboxymethyl cellulose and pectin. The membrane characterization included identifying the functional groups of each polymer, the surface appearance, and the absorption capacity of aqueous media, simulating the exudates of skin diseases. Membrane weight loss was close to 50 % during the first day, and they preserved their integrity throughout the study. The mechanical characteristics demonstrated that the membranes with adjuvants are flexible and tough. The rigidity of the membranes was between 10.49 MPa and 22.65 MPa, and this rigidity decreased with the addition of chitosan and pectin. With chitosan, the elongation at break (8.25 %) was higher but the elastic modulus (450.78 MPa) was lower than those recorded with the other polymers. The effect against Staphylococcus aureus occurs due to chitosan and only by contact. In particular, an inhibition zone increased with the addition of chitosan (178.21 mm2). However, carboxymethyl cellulose showed the least shrinkage (4.4 %). Therefore, it is possible to produce nanofibers to make chitosan and polyvinyl alcohol membranes with improved functional characteristics by the addition of adjuvant agents as an alternative to other skin healing materials.

This paper deals with the design of robust regulation for both angular speed stability enhancement and voltage in synchronous generator machines with an excitation control system. The designed controller is based on the block control technique combined with a sliding-mode (SM) control approach. The block control is used to design a nonlinear sliding manifold with the desired stability property. In order to attenuate the chattering effect which can appear in the presence of the exciter's unmodeled dynamics, a high-order SM algorithm and a robust exact differentiator are employed. The efficiency of the proposed controller, i.e., robustness and high accuracy, is verified via simulations. [ABSTRACT FROM AUTHOR]

Synchronous generators have a natural different time scale dynamics. That is why, for modelling and control design in such systems, the methods of singular perturbations are widely used. In this paper the possibilities of sliding mode control design for synchronous generators are analysed. With this aim the concept of singular perturbation is revised in order to use it for relay control systems. The obtained results are used for sliding mode control of synchronous generator. [ABSTRACT FROM AUTHOR]