Electron microscopic length

Fig. 5. Scanning electron microscope (SEM) images of aligned MWCNT of uniform length (40 pm) and diameters (30-50 nm). Scales bars are 10 pm (top) and 1 pm (bottom) (Courtesy of Drs. M. Terrones and D. R. M. Walton).

It is notable that the GC samples in Table 4.1 are much too short for the Intermediate Zone formula to apply out to 120 ns. The formulas for subsequent zones of C (t) (Eqs. 4.38—4.41) are employed as needed and yield the same value of a for both 230- and 590-bp samples.(146) The 590-bp sample initially exhibited a threefold higher value, which relaxed over several months, during which time many very small fragments dissociated from, or annealed out of, the predominant 590-bp species. This was tentatively attributed to the presence of branched structures, which exhibit high affinity sites for ethidiuny in the original material. Both gel electrophoretic and electron microscopic 147 1 evidence for branched structures in poly(dG-dC) were noted.(146) The 500-bp length from gel electrophoresis was confirmed by sedimentation.(146)... 

Numerous tropocollagen molecules (mass 285 kDa, length 400 nm) aggregate extracell-ularly into a defined arrangement, forming cylindrical fibrils (20-500 nm in diameter). Under the electron microscope, these fibrils... 

---