Category: Research

from the precision-vision dept.
ChrisPhoenix notes these two items on work that probes the fine structure of materials and atoms:
"According to a Physics News Update article, A Sharp Gamma-Ray Hologram, physicists in Krakow have made a gamma ray hologram of an iron crystal resulting in 3D images of the local crystal structure with half-angstrom spatial resolution. They've solved the "twin image" problem and hope to be mapping local magnetic environment soon. The article describes the difference between gamma ray holography and X-ray holography.

"Another physnews article, The Most Spherical Thing, describes a search for electric dipoles in atoms. The interesting thing is the precision of the measurement. They looked for a change in precession, and couldn't find it at a level of 0.4 nano-Hz. This corresponds to an energy shift of less than 2.6 x 10^-43 Joule, the smallest that has ever been measured. After nanotech comes femtotech…"

from the inspired-by-nature dept.
Saturngraphix spotted this press release about Purdue chemist Hicham Fenniriís work using DNA to guide the self-assembly of nanoscale structures: "Inspired by nature's own building blocks, Purdue University researchers are using the same principle that makes DNA strands link together to create tiny structures that may someday be used to manufacture molecular wires and other components for use in nanometer-sized electronic devices."

According to the release, the new technique will allow scientists to use self-assembly techniques to develop nanoscale structures with specific dimensions and chemical properties, and may help pave the way for designing new materials, electronic devices and drug delivery systems. Fenniriís research will be detailed in the 25 April 2001 issue of the Journal of the American Chemical Society.

from the biomimicry dept.
SteveLenhert at About.com writes of an short article posted there that provides a brief overview of DNA-based nanomechanics. He writes writes "This article summarizes and references recent research on DNA based nanomechanics, and discusses implications in vivo."

from the step-by-step dept.
A team of researchers in Japan have reported on a potentially useful phenomenon: reversible, light-induced nanometer-scale changes in the shape of a crystal. In a paper that appeared in the 2 March 2001 issue of Science, they report that irradiating the crystal with ultraviolet light induced the formation of regular, 1 nm size steps (the height of one molecular layer). The process could be reversed using light at another (visible) wavelength. The authors conclude:
ì The surface morphological changes can be explained by the molecular structural changes of diarylethenes regularly packed in the single crystal. These crystals could potentially be used as photodriven nanometer-scale actuators.î

Read more for the full abstract and citation in Science. Online access to the full paper requires a subscription to the journal.

from the unnatural-selection dept.
vik points out an item about researchers at the Massachusetts General Hospital in Boston who have been developing proteins with specific binding affinity by pseudo-evolutionary processes, which appeared on Natureís Science Update site. Researchers Anthony Keefe and Jack Szostak have developed a method to indetify proteins to do a predetermined job from a vast number of random genes. The article makes an explicit connection to the potential of protein design as a pathway toward nanotechnology:
"It's 20 years since Eric Drexler, one of the prophets of nanotechnology, suggested that proteins could be engineered, and that molecular machines could be used in computing or medicine. But protein design has proved damnably difficult, because of our inability to predict how a linear sequence of amino acids will fold up into a three-dimensional protein. An evolutionary approach might sidestep this problem."

Drexler's 1981 paper in the Proceedings of the National Academy of Sciences USA, which first proposed the protein engineering pathway, is cited.

vik writes: "An evolutionary approach to protein design may be more fruitful than protein-folding predictions in producing either protein-based machinery or using custom proteins as templates for the catalysis of nanoscale components."

from the Totally-tubular dept.
brian wang writes "Speaking at an American Physical Society meeting in Seattle, Phaedon Avouris of IBM described the creation of a carbon nanotube integrated circuit, with a thousand nanotubes acting like transistors . . . Speaking at an APS meeting in Seattle, Avouris described how, in a mixed batch of nanotubes, one can short out the metallic nanotubes (with a surge of voltage) while leaving the semiconducting ones intact for use as circuit elements."

But, as DanKindsvater notes, AIP Physics News later ran this correction about this item: "Researchers at IBM have not yet made an integrated circuit of carbon nanotubes . . . Rather, Phaedon Avouris and Philip Collins of IBM have announced a scheme for the fabrication of large arrays of nanotubes. They also put together one p-type nanotube transistor and one n-type transistor to form a working logic NOT gate."

Read more for other highlights in nanotube research reported at the APS conference.

from the STM-nano-fabrication dept.

John Faith points out an article in EE Times in which Japanese nanotechnology research scientist Masakazu Aono, head of the surface and interface laboratory at Japan's Institute of Physical and Chemical Research, claims his team is now only months away from developing Japan's first single-electron tunneling transistor capable of operating at room temperature ("Researchers close in on single-atom switch," by P.Kallender, 7 March 2001).

The transistor Aono is developing consists of three, 3-nanometer-wide "wires" that act as a source and a drain, each separated from a well containing a 10-atom-diameter cluster of 500 silver atoms that acts as a capacitor. On the other side of the separation lies the gate, which sits 4 nm from the capacitor, with the whole unit resting on a graphite substrate. The circuit works by exploiting the difference in the quantum conductance potentials created between the source drain and the capacitor. When carrying a single electron, current can flow through source and drain, said Aono, but 1 volt placed at the gate adds a second electron to the capacitor, thus raising its potential and closing the circuit.
"We can make an atomic switch in a cluster of silver atoms," he said. "The island is so small we are talking about a one-electron effect circuit."

Read more for additional details . . .

from the One-dimensional-nanotechnology dept.

SaturnFX calls our attention to an interesting Georgia Tech press release on Science Daily. According to the release, researchers at the Center for Nanoscience and Nanotechnology have created a new class of nanometer-scale structure that could be the basis for inexpensive ultra-small sensors, flat-panel display components and other electronic nanodevices. The researchers claim these extremely thin and flat structures — made of semiconducting metal oxides and dubbed "nanobelts" — offer significant advantages over the nanowires and carbon nanotubes.

The ribbon-like nanobelts are chemically pure, structurally uniform and largely defect-free, with clean surfaces not requiring protection against oxidation. Each is made up of a single crystal with specific surface planes and shape. Typical width of the nanobelts is from 30 to 300 nanometers, with a thickness of 10-15 nanometers. Some have been produced in lengths of up to a few millimeters, though most are tens to hundreds of micrometers long. The work is described in the March 9 issue of Science.

"Current research in one-dimensional systems has largely been dominated by carbon nanotubes," said Zhong Lin Wang, professor of Materials Science and Engineering and director of the Center for Nanoscience and Nanotechnology at the Georgia Institute of Technology. "It is now time to explore other one-dimensional systems that may have important applications for nanoscale functional and smart materials. These nanobelts are the next step in developing structures that may be useful in wider applications."

The press release also appears on the Georgia Tech web site, with a link to images. The research was sponsored by Georgia Tech, and a provision patent application has been filed on the new structures.