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October 5, 2009 - Volume 87, Number 40
- p. 36
Science & Technology Concentrates
More Science & Technology Concentrates
- Microgel Enzyme Inhibitor
- A molecularly imprinted polymer selectively inhibits trypsin better that one of the enzyme’s known small-molecule inhibitors
- Element 114 Confirmed
- Eight-day-long atom-smashing experiment reproduces 10-year-old result
- Improved Selectivity In Making Metallic Carbon Nanotubes
- A new method to prepare single-walled carbon nanotubes allows better control over the tubes’ chirality and thus their conductivity properties
- Evaporating Polymer Produces Webby Patterns
- Controlling the evaporation of a drop of diblock copolymer under just the right conditions leads to self-assembly of weblike thin films
- Engineered Response To A Faux Dopamine
- Mutating one amino acid in a dopamine receptor makes a new tool for dissecting brain signals
- Serotonin Harnesses Small RNAs To Strengthen Synapses
- A study reveals that the neurotransmitter can regulate microRNAs and thus protein synthesis, which could shed light on long-term memory
- Structure Prediction Cautionary Tale
- Uneven analysis of crystal polymorphs suggests that extra caution is required with computational prediction of crystal structures
- Colorful Organic Nanocolloids
- Confining discreet numbers of dye molecules in liquid crystals yields a colorful array of organic-based materials
Topics Covered
A new way of preparing single-walled carbon nanotubes allows chemists to control the tubes’ chirality, which is the property that renders their conductivity behavior either semiconducting or metallike (Science 2009, 326, 116). Standard nanotube synthesis methods usually produce a mixture of semiconducting and metallic tubes, which are difficult to separate. A team led by Avetik R. Harutyunyan of the Honda Research Institute USA, in Columbus, Ohio, used iron nanocatalysts deposited onto a SiO2/Si framework and varied the environment in which the catalysts were annealed—using a helium or argon environment, different ratios of H2 and H2O, and different temperatures. The right combination of these variables produced nanotubes from methane that were up to 91% metallic, compared with the typical 33%. Although numerous research groups have had success in devising ways to control carbon nanotube chirality, the mechanisms have remained elusive. The new work by Harutyunyan and coworkers, however, identifies a correlation between catalyst morphology and the resulting nanotube electronic structure. “Our results indicate that, with further optimization, direct control over nanotube structure during growth may well be feasible,” the researchers write.
- Chemical & Engineering News
- ISSN 0009-2347
- Copyright © 2009 American Chemical Society
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