Category: Research

from the gene-blues dept.
A study by researchers at the Whitehead Institute for Biomedical Research and University of Hawaii that one method used for cloning animals can produce seemingly normal-looking clones that harbor serious abnormalities affecting gene expression that may not manifest themselves as outward characteristics. The research was reported in the July 6 issue of Science.
In addition, their work found that mice cloned from embryonic stem cells exhibited a wide variety in gene expression, as well as extremely unstable gene expression in the stem cells themselves. This may shed light on why current cloning methods produce few live births and abnormally large survivors.
However, many of the cloned mice in the study survived to adulthood, however, meaning that mammals may be more tolerant of this type of widespread gene dysregulation during development than previously suspected.

from the molectronics dept.
Researchers in the Netherlands have created a single-electron transistor (SET) made from a single carbon nanotube, whose minute size and low-energy requirements should make it an ideal device for molecular computers. The Dutch nanotube single electron transistor, the first to operate efficiently at room temperature, was described in the 6 July 2001 issue of Science.
"We've added yet another important piece to the toolbox for molecular electronics," said author Cees Dekker of Delft University of Technology, in the Netherlands. Dekker and his colleagues started with a single carbon nanotube, and used the tip of an atomic force microscope to create sharp bends, or buckles, in the tube. These buckles worked as the barriers, only allowing single electrons through under the right voltages. The whole device was only 1 nm wide and 20 nanometers long.

from the nanoslosh dept.
Proteins are far more active and dynamic than scientists have imagined, say researchers at the University of Pennsylvania School of Medicine. Their study, published in the 23 May 2001 issue of Nature, affords the first comprehensive view scientists have had of a proteinís internal motion. "The interior of a protein is much more liquid-like than scientists originally anticipated. Everything is moving, and it's moving all the time, very fast," said A. Joshua Wand, PhD, Professor of Biochemistry and Biophysics at Penn and principal author of the study. "The really exciting thing is they move so much that, potentially, it dramatically influences how they work," Wand said.

from the Molectronics dept.
An article in Science News ("Chemists decorate nanotubes for usefulness", by J. Gorman, 23 June 2001) describes work by researchers who have developed a new technique for attaching groups of atoms to the sides of carbon nanotubes, creating compounds with extraordinary strength and conductivity. The article is not available at the SN website, but is reprinted on the SmallTimes website. The work is described in a recent issue of the Journal of the American Chemical Society (123:6536).
The research team was led by James Tour of Rice University and Paul Weiss of Pennsylvania State University. The article suggests the functionalized carbon nanotubes could be used for making electronic circuits that are far tinier than today's silicon-based circuitry. Doing so will require chemically hooking carbon nanotubes to other microscopic electronic components, comments Weiss. One of the functional groups that the Rice researchers successfully attached to carbon nanotubes has exhibited both memory and switching behaviors necessary for electronic devices, says Tour. The researchers are investigating whether a nanotube and its functional groups retain their desirable strength, conductivity, and chemical traits after they're combined.

As noted here on nanodot, a team led by Tour and Weiss announced in June 2001 that they have demonstrated single molecules that switch between "on" and "off" states based in part on conformational changes.

from the step-by-step dept.
Researchers at Stanford University led by chemistry professor W. E. Moerner have gained further detail on how the kinesin molecular motor pulls objects along microtubule tracks inside cells. Their studies reveal that while one end of a kinesin molecule holds onto its cargo, the other end uses a remarkable two-headed structure to grab the microtubule and pull the cargo forward – a process called "kinesin walking" The work is described in the June 2001 issue of Nature Structural Biology.

As reported here on nanodot in June 2001, other research indicates kinesin systems may also harness the energy of random Brownian motions to move along microtubules.

Kinesin molecular motors are also employed in the microtubule molecular shuttles developed by a team led by Viola Vogel at the University of Washington (Seattle) Center for Nanotechnology. The shuttles are capable of moving cargo along engineered paths. Vogel and her co-workers have demonstrated methods of controlling the direction of motion of microtubules on engineered kinesin tracks, how to load cargo covalently to microtubules, and how to exploit ultraviolet light to turn the shuttles on and off sequentially. These are the first steps in the development of a tool kit to utilize molecular motors for the construction of nanoscale assembly lines. This work was described at the 2000 Foresight Conference in November 2000.

from the fast-spin dept.
Researchers with the California NanoSystems Institute (CNSI) have developed a new way to manipulate optically quantum spin states on ultrafast time scales (femtoseconds). They suggest that the ability to quickly manipulate electron spins could pave the way for all-optical quantum computation in solids by loosening the stringent requirements on coherence times. In a paper published in the 29 June 2001 issue of Science ("Ultrafast Manipulation of Electron Spin Coherence"), a team led by University of California at Santa Barbara (UCSB) physicist David Awschalom described their experiments. Awschalom is director of the UCSB Center for Spintronics and Quantum Computation, a central component of the new California NanoSystems Institute (CNSI) located jointly at UCSB and UCLA.

For more information about CNSI, see Foresight Update #43.