Interesting tech developments in nanotech, nanostructured materials, etc.
Ken Novak's Weblog
Monday, August 29, 2005
Major advance producing carbon nanotube sheets
: "University of Texas at Dallas (UTD) nanotechnologists and an Australian colleague have produced transparent carbon nanotube sheets that are stronger than the same-weight steel sheets and have demonstrated applicability for organic light-emitting displays, low-noise electronic sensors, artificial muscles, conducting appliqués and broad-band polarized light sources that can be switched in one ten-thousandths of a second.
Carbon nanotubes are like minute bits of string, and untold trillions of these invisible strings must be assembled to make useful macroscopic articles that can exploit the phenomenal mechanical and electronic properties of the individual nanotubes. In the Aug. 19 05 issue of the prestigious journal Science, scientists from the NanoTech Institute at UTD and a collaborator, Dr. Ken Atkinson from Commonwealth Scientific and Industrial Research Organization (CSIRO), a national laboratory in Australia, report such assembly of nanotubes into sheets at commercially useable rates.
Starting from chemically grown, self-assembled structures in which nanotubes are aligned like trees in a forest, the sheets are produced at up to 7 meters per minute by the coordinated rotation of a trillion nanotubes per minute for every centimeter of sheet width. By comparison, the production rate for commercial wool spinning is 20 meters per minute. Unlike previous sheet fabrication methods using dispersions of nanotubes in liquids, which are quite slow, the dry-state process developed by the UTD-CSIRO team can use the ultra-long nanotubes needed for optimization of properties. " More about applications, to solar cells, batteries, fuel cells, medicine, and engineering at WorldChanging. 9:17:47 AM
Thursday, August 18, 2005
Friday, August 12, 2005
Study of super-hard ceramics: "A discovery reported in the August 5 issue of Science could speed the design of materials that approach the hardness of diamond yet remain supple enough to be worked like metal. In a massive computer simulation involving 128 computer processors and nearly 19 million atoms, materials scientist Izabela Szlufarska of the University of Wisconsin-Madison and colleagues at University of Southern California demonstrated the precise atomic mechanisms that explain why "nanostructured" ceramic materials-some of the hardest substances known-also exhibit unusual pliability.
Unlike other exceptionally hard materials, these advanced ceramics tend to bend rather than break, meaning they could be shaped into extremely long-lasting yet lightweight parts for everything from automobile engines and high-speed machining tools to medical implants in the body.
Simulations can help to answer this by providing a level of detail unavailable to experiments. Using atomic-scale simulations, the team observed for the first time how atoms moved and interacted as a super-hard ceramic deformed under stress. The advance has not only provided unprecedented insight into the properties of these materials, but also a tool that researchers can use to systematically nano-engineer them. ..
The researchers next want to learn how to control the crossover point so as to engineer greater hardness into nano-crystalline silicon carbide without compromising pliability. For example, they could vary the volume of the grain boundaries or the size of the grains. Impurities, or dopants, might also be added to the grain boundaries to make the material stronger. Key to it all is the enormous computing power that allows scientists to simulate the material’s atomic details. "The experiments and devices have become smaller and smaller, while the simulations have grown larger and larger," says Szlufarska. "This is a unique time when the leading edge of materials design is exactly at the same length scale where fully atomic simulations are possible." " 2:21:50 PM
Towards a green nanotechnology: Review of the issues and early studies. "nanotechnology has been the subject of projections concerning its possible environmental risks well before its wide-scale commercialization. Raising such questions when nanotechnology is still in its infancy may result in better, safer products and less long-term liability for industry.
The rapidly developing nanomaterials industry is the nanotechnology that is most likely to affect our lives first. .. In the environmental technology industry alone, nanomaterials will enable new means of reducing the production of wastes, using resources more sparingly, cleaning up industrial contamination, providing potable water, and improving the efficiency of energy production and use. Commercial applications of nanomaterials currently or soon to be available include nano-engineered titania particles for sunscreens and paints, carbon nanotube composites in tires, silica nanoparticles as solid lubricants, and protein-based nanomaterials in soaps, shampoos, and detergents.
The production, use, and disposal of nanomaterials will inevitably lead to their appearance in air, water, soils, or organisms. Research is needed to ensure that nanomaterials, and the industry that produces them, evolve as environmental assets rather than liabilities. Unfortunately, little is known about the potential environmental impacts of nanomaterials...
An encouraging trend is that the methods used to produce nanomaterials often become “greener” as they move from the laboratory to industrial production. Setting aside the issue of nanomaterials’ toxicity, preliminary results suggest that fabricating nanomaterials entails risks that are less than or comparable to those associated with many current industrial activities. ..
It would be naïve to imagine that nanotechnology will evolve without risks to our health and environment. While attempting to halt the development of nanomaterial-inspired technologies would be as irresponsible as it is unrealistic, responsible development of these technologies demands vigilance and social commitment. " 2:05:03 PM
Tuesday, August 02, 2005
Nanotechnology kills cancer cells
: Another study with light-activated nanoparticles. "The technique works by inserting microscopic synthetic rods called carbon nanotubules into cancer cells. When the rods are exposed to near-infra red light from a laser they heat up, killing the cell, while cells without rods are left unscathed. ..
Under normal circumstances near-infra red light passes through the body harmlessly. But the Stanford team found that if they placed a solution of carbon nanotubules under a near-infra red laser beam, the solution heated up to about 70C in two minutes. They then placed the tubules inside cells, and found they were quickly destroyed by the heat generated by the laser beam. .. The next step was to find a way to introduce the nantubules into cancer cells, but not healthy cells. The researchers did this by taking advantage of the fact that, unlike normal cells, the surface of cancer cells is covered with receptors for a vitamin known as folate. They coated the nanotubules with folate molecules, making it easy for them to pass into cancer cells, but unable to bind with their healthy cousins. Exposure to the laser duly killed off the diseased cells, but left the healthy ones untouched.
The researchers believe it should be possible to refine the technique still further, for instance by attaching an antibody to a nanotubule to target a particular kind of cancer cell. 4:18:48 AM