The majority of carboxylic acid groups formed after treatment of a single‐walled carbon nanotube (SWCNT) material with nitric acid are present on carboxylated carbonaceous fragments (CCFs) (see figure). These CCFs are removed from the SWCNTs by treatment with NaOH solution and identified as carriers of the COOH functionality, implying that previous reports claiming side‐wall functionalization of the SWCNTs with COOH groups should be reconsidered.
Purification and opening of carbon nanotubes has been carried out by treatment of as-made single-wall carbon nanotubes (SWNTs) with pure steam at 1 atm pressure. Treated samples have been characterized by high-resolution transmission electron microscopy and IR and Raman spectroscopy. Comparison between the steam purification and the standard nitric acid purification treatment shows that steam is less aggressive toward damage to the tubular nanotube wall structure and forms fewer functional groups.
Lattice stick number sL(K) is defined to be the minimal number of sticks required to construct a polygonal representation of the knot K in the cubic lattice. In this paper, we give lattice stick numbers of small knots such as 31 and 41. More precisely we prove that sL(31) = 12 and sL(K) ≥ 14 for any other non-trivial knot K.
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