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          | Description: 
             The top scanning tunneling 
            microscope image shows an armchair nanotube, which has rows of hexagonal 
            carbon molecules running along its axis. The bottom image shows a 
            zigzag nanotube, which has rows of carbon molecules winding around 
            its circumference. | 
         
         
          | Source: 
             Lieber Group, Harvard University | 
         
         
          Story:  How 
            metallic are metal nanotubes? 
            TRN May 30, 2001  | 
         
         
          | TRN Categories: 
             Materials Science and Engineering 
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          | Form: 
             Still | 
         
       
      
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