Pre-intercalation of long chain fatty acid in the interlayer space of layered silicates and preparation of montmorillonite/natural rubber nanocomposites

A series of long chain fatty acids was intercalated into the interlayer space of organo montmorillonite (OMt) and a gradual expansion of the interlayer space was observed as the chain length of the fatty acid increased. The fatty acid with 22 carbon atoms (docosanoic acid) was found to offer a highest interlayer space among the fatty acids under consideration. This fatty acid was selected further to modify OMt and subsequently utilized as reinforcing fillers in natural rubber (NR) matrix. Wide angle X-ray diffraction (WAXD). Fourier transform infrared (FTIR) spectroscopy and contact angle measurement indicated successful intercalation of the fatty acid into the interlayer space of the clay minerals. The main objective of such intercalation is to make clay minerals suitable for the preparation of rubber nanocomposites. especially when using non-polar rubbers. Docosanoic acid intercalated Mt was successfully dispersed in NR matrix as confirmed by WAXD and transmission electron microscopy (TEM). As a result, the mechanical properties were found to be improved in a remarkable way. Improvement of similar to 114% in tensile strength and similar to 203% in modulus at 300% elongation was observed. These results were correlated with the morphological data obtained from WAXD and TEM. (C) 2012 Elsevier B.V. All rights reserved

Structure/function studies on cytoskeletal proteins in Dictyostelium amoebae as a paradigm

The actin cytoskeleton in motile non-muscle cells is being regulated by a large number of actin-binding proteins. A deeper insight into the complex nature of the dynamic rearrangements of the microfilament system during cell movement requires an experimental system that allows the combined application of biochemical, biophysical, cell biological and molecular methods. Dictyostelium amoebae are well suited especially for a genetic approach because they are amenable to gene disruption, antisense and gene tagging techniques. The actin-binding proteins profilin, hisactophilin and protovillin are being described in this context as typical examples that either bind to G-actin, or anchor the actin cytoskeleton to the plasma membrane, or are structurally similar to vertebrate proteins but distinct in their functions