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Magnetic/pH-sensitive κ-carrageenan/sodium alginate hydrogel nanocomposite beads: Preparation, swelling behavior, and drug delivery
, Article Journal of Biomaterials Science, Polymer Edition ; Vol. 25, issue. 17 , 2014 , p. 1891-1906 ; Rahmani, Z ; Karami, S ; Pourjavadi, A ; Sharif University of Technology
Abstract
This work describes the preparation of magnetic and pH-sensitive beads based on κ-carrageenan and sodium alginate for use as drug-targeting carriers. Physical cross-linking using K+/Ca2+ ions was applied to obtain ionic cross-linked magnetic hydrogel beads. The produced magnetite beads were thoroughly characterized by TEM, SEM/EDS, XRD, FTIR, and VSM techniques. While the water absorbency (WA) of magnetic beads was enhanced by increasing the weight ratio of κ-carrageenan, introducing magnetic nanoparticles caused a decrease in WA capacity from 15.4 to 6.3 g/g. Investigation on the swelling of the hydrogel beads in NaCl, KCl, and CaCl2 solutions revealed the disintegration of beads depending...
Power amplifiers linearization based on digital predistortion with memory effects
, Article 2009 International Conference on Computer and Electrical Engineering, ICCEE 2009, 28 December 2009 through 30 December 2009, Dubai ; Volume 1 , 2009 , Pages 26-29 ; 9780769539256 (ISBN) ; Mirzakuchaki, S ; Karami, S ; Sharif University of Technology
Abstract
Power amplifiers require linearization in order to reduce adjacent inter-modulation distortion without losing efficiency. Digital predistortion is a cost effective method to achieve this goal and it needs an accurate model of the amplifier. Most of the amplifier models are based on memoryless modeling. This kind of modeling is simple but it's not accurate enough if linearization is important; and also for wide band modulations like QAM, we should consider the memory effects of power amplifiers. © 2009 IEEE