Sunday, November 27, 2005

Nanoscale hydrodynamics: Enhanced flow in carbon nanotubes


Nature 438, 44 (3 November 2005) | doi:10.1038/43844a

"Nanoscale hydrodynamics: Enhanced flow in carbon nanotubes
Mainak Majumder1, Nitin Chopra1, Rodney Andrews2 and Bruce J. Hin

"Nanoscale structures that could mimic the selective transport and extraordinarily fast flow possible in biological cellular channels would have a wide range of potential applications. Here we show that liquid flow through a membrane composed of an array of aligned carbon nanotubes is four to five orders of magnitude faster than would be predicted from conventional fluid-flow theory. This high fluid velocity results from an almost frictionless interface at the carbon-nanotube wall.

"1. Chemical and Materials Engineering Department, University of Kentucky, Lexington, Kentucky 40506, USA
2. Center for Applied Energy Research, Lexington, Kentucky 40511, USA"

Scientists See Light That May be from First Objects in Universe

SpaceRef - Your Space Reference

"This new Spitzer discovery agrees with observations from the NASA Cosmic Background Explorer satellite from the 1990s that suggested there may be an infrared background that could not be attributed to known stars. It also supports observations from the NASA Wilkinson Microwave Anisotropy Probe from 2003, which estimated that stars first ignited 200 million to 400 million years after the Big Bang.
'This difficult measurement pushes the instrument to performance limits that were not anticipated in its design,' said team member Dr. S. Harvey Moseley, instrument scientist for Spitzer. 'We have worked very hard to rule out other sources for the signal we observed.' "

Saturday, November 26, 2005

"Bright Infrared Emission from Electrically Induced Excitons in Carbon Nanotubes"


Nanotube films as shock absorbers, nanotubes as infrared emitters, these things are a technological explosion! I'm fascinated, but can't hope to keep up with the field.

"Bright Infrared Emission from Electrically Induced Excitons in Carbon Nanotubes
Jia Chen,1* Vasili Perebeinos,1 Marcus Freitag,1 James Tsang,1 Qiang Fu,2 Jie Liu,2 Phaedon Avouris1*
We used the high local electric fields at the junction between the suspended and supported parts of a single carbon nanotube molecule to produce unusually bright infrared emission under unipolar operation. Carriers were accelerated by band-bending at the suspension interface, and they created excitons that radiatively recombined. This excitation mechanism is 1000 times more efficient than recombination of independently injected electrons and holes, and it results from weak electron-phonon scattering and strong electron-hole binding caused by one-dimensional confinement. The ensuing high excitation density allows us to observe emission from higher excited states not seen by photoexcitation. The excitation mechanism of these states was analyzed.
1 IBM Research Division, Thomas J. Watson Research Center, Post Office Box 218, Yorktown Heights, NY 10598, USA.
2 Department of Chemistry, Duke University, Durham, NC 27708, USA. "

"Loss of Fear Factor Makes Timid Mouse Bold"

"Eric R. Kandel at Columbia University, found that the protein stathmin is critical for both innate and learned fear"