The feasibility of grafting poly( methyl acrylate) and poly[ 1-(methoxycarbonyl) ethylene] onto chitosan, poly-P( 1 +4)-2-amino-2-deoxy-D-glucose, was investigated. The grafting reaction was carried out in aqueous solution by using ferrous ammonium sulfate (FAS) in combination with H,O, as redox initiator. The effects of such reaction variables as chitosan, monomer and initiator concentrations, reaction time, and reaction temperature were determined. Through this study the grafting reaction could be optimized. The grafting yield reached its maximum 1037 Copyright 0 1995 by Marcel Dekker, Inc.Downloaded by [Michigan State University] at 23:07 27 December 2014 1038 YAZDANI-PEDRAM ET AL.value of 332% when 0.3 g chitosan was copolymerized with 3 mL monomer at 7OoC for 120 minutes with [FAS] = 6 x lo-' M, [H,O,] = 6 x 10 -3 M, and 8 mL water. The grafted chitosan was found to be insoluble in solvents for chitosan and solvents for poly(methy1 acrylate), but did show swelling in dilute acetic acid, methanol, acetone, and in an ethanol/2% acetic acid 1 : 1 mixture. The thermal stability of chitosan and grafted chitosan were studied by dynamic thermogravimetric analysis. The results show that the graft copolymer is thermally more stable than pure chitosan. The overall activation energy for graft copolymerization was estimated to be 32.8 kcal/mol.

No abstract

Bone involvement occurs infrequently in patients with cat scratch disease and is not always associated with specific signs. Cat scratch disease must be suspected in patients with fever of unknown origin presenting multifocal lesions on BS.

Abnormalities of cortical development are frequent causes of refractory epilepsy. Among these pathologies, focal cortical dysplasia (FCD) is a heterogeneous group of disorders pathologically characterized by loss of normal cortical structure. Two distinct entities with different etiology have been described (FCD type I and FCD type II Taylor). This study presents relevant case studies, highlighting the pathological features in magnetic resonance imaging.