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Large-scale SiC nanowires were prepared by directly annealing polysiloxane and wood powder composites without catalyst assistant at 1420 °C under argon atmosphere. SiC nanowires are up to tens of micrometers in length and the diameters are in the range of 30-150 nm. Most nanowires are smooth and straight in morphology. High-resolution TEM image shows that SiC nanowires grow along the [111] direction. The vapor-solid mechanism was proposed to explain the growth procedure of SiC nanowires. The present work provides an efficient and simple strategy for large-scale production of SiC nanowires. [ABSTRACT FROM AUTHOR]

For the first time the computed mechanisms for the novel reaction of 2-naphthol with N-methyl- N-phenylhydrazine, leading to 1-amino-2-naphthol (Tang et al., J Am Chem Soc 2008, 130, 5840), have been investigated using the density functional theory. Four distinct possible pathways were evaluated: two amination mechanisms with the attack of NH2 group respectively at the α-position C1 and β-position C3 atoms of 2-naphthol (pathways 1 and 2) as well as two rearrangement processes with displacement of the phenolic hydroxyl group followed by the benzidine-like rearrangement at the α-position C1 and β-position C3 atoms of 2-naphthol, respectively (pathways 3 and 4). Solvent effect has been tested based on the optimized geometries of the stationary points in solution at the B3LYP/PCM/6-31+G(d,p) level of theory with an averaged dielectric constant of binary solvent. Single-point energies of the optimized structures have been calculated using three hybrid density functionals, B3LYP, MPW3LYP, and B3PW91 with the 6-311++G(3df,2p) basis set. Our computed results clearly manifest that pathway 1 (α-amination) has the highest possibility to occur, with the Gibbs free energies being lower by 6 to 20 kcal/mol compared with the other three pathways, which leads to 1-amino-2-naphthol and N-methylaniline as products. It is in excellent agreement with the experimental observation. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011 [ABSTRACT FROM AUTHOR]