Enhanced performance of nano-sized SiC reinforced Al metal matrix nanocomposites synthesized through microwave sintering and hot extrusion techniques

In the present study, nano-sized SiC (0, 0.3, 0.5, 1.0 and 1.5 vol%) reinforced aluminum (Al) metal matrix composites were fabricated by microwave sintering and hot extrusion techniques. The structural (XRD, SEM), mechanical (nanoindentation, compression, tensile) and thermal properties (co-efficient of thermal expansion- CTE) of the developed Al-SiC nanocomposites were studied. The SEM/EDS mapping images show a homogeneous distribution of SiC nanoparticles into the Al matrix. A significant increase in the strength (compressive and tensile) of the Al-SiC nanocomposites with the addition of SiC content is observed. However, it is noticed that the ductility of Al-SiC nanocomposites decreases with increasing volume fraction of SiC. The thermal analysis indicates that CTE of Al-SiC nanocomposites decreases with the progressive addition of hard SiC nanoparticles. Overall, hot extruded Al 1.5 vol% SiC nanocomposites exhibited the best mechanical and thermal performance as compared to the other developed Al-SiC nanocomposites.     

Progress in biomimetic carbohydrate recognition

The importance of carbohydrate recognition in biology, and the unusual challenges involved, have lead to great interest in mimicking saccharide-binding proteins such as lectins. In this review, we discuss the design of artificial carbohydrate receptors, focusing on those which work under natural (i.e. aqueous) conditions. The problem is intrinsically difficult because of the similarity between substrate (carbohydrate) and solvent (water) and, accordingly, progress has been slow. However, recent developments suggest that solutions can be found. In particular, the “temple” family of carbohydrate receptors show good affinities and excellent selectivities for certain all-equatorial substrates. One example is selective for O-linked β-N-acetylglucosamine (GlcNAc, as in the O-GlcNAc protein modification), while another is specific for β-cellobiosyl and closely related disaccharides. Both show roughly millimolar affinities, matching the strength of some lectin–carbohydrate interactions.