Welding at the nanoscale -- Carbon nanotubes can carry large amounts of electrical current without losing heat, making them ideal materials for nanoscale wires. Now researchers at Rensselaer and the Max Planck Institute in Germany report a way to weld these tiny tubes together end-to-end, overcoming a major obstacle to realizing nanotube-based devices. By passing a high current through a thin film with nanotubes dispersed across its surface, they generated visible flashes of light -- similar to the familiar arc from a welder's torch. Further investigation revealed that the flashes occur at junctions where overlapping carbon nanotubes are welded together. Current methods to make nanowires require bombarding the surface with electrons or other charged particles, which may not be easily scalable. The researchers suggest that their new technique could provide a viable tool for producing nanowires cost-effectively.
(Q1.1, Monday, Nov. 28, 8:30 a.m., Room 209, Hynes, presented by Saurabh Agrawal, a graduate student in materials science and engineering at Rensselaer. The principle investigator is G. Ramanath, Rensselaer associate professor of materials science and engineering.)
Carbon nanotubes for water treatment -- While activated carbon has long been the standard for removing organic contaminants from drinking water, a new study suggests that carbon nanotubes have significant potential as better materials for water purification. In this talk, researchers from Rensselaer and Banaras Hindu University in India present data indicating that carbon nanotubes may do a better job than activated carbon at removing trichloroethylene (TCE), an industrial solvent that, according to the National Research Council, is one of the most frequently detected groundwater contaminants in the United States. The small pores in activated carbons can get plugged by natural compounds in water, which reduces their effectiveness. Carbon nanotubes, on the other hand, attract pollutants because of their surface characteristics, not the presence of pores.
(S6.9, Wednesday, Nov. 30, 10:45 a.m., Room 203, Hynes, presented by Reena Srivastava, a graduate student in environmental engineering at Rensselaer. The principle investigator is James "Chip" Kilduff, Rensselaer professor of environmental engineering.)
Stem cells and biomaterials -- To create artificial bones and other biomaterials, scientists need specially designed scaffolds that can direct how cells grow into body tissues. A new study from researchers at the Rensselaer Nanotechnology Center provides much-needed insight into this process, which sits at the intersection of biotechnology and nanotechnology. The team examined the behavior of mesenchymal stem cells (MSCs), which are derived from bone marrow, on a number of ceramic materials that could be used as scaffolds. They found that the size and chemistry of the nanoparticles that make up the ceramic materials has an impact on the way MSCs stick to the surfaces, and that one protein is primarily responsible for this impact: vitronectin, one of the major adhesive proteins found in human blood. This fundamental knowledge will help tissue-engineering researchers design the next generation of biomaterials for orthopedic applications, they say.
(K2.2, Wednesday, Nov. 30, 2 p.m., Room 204, Hynes, presented by Richard W. Siegel, the Robert W. Hunt Professor of Materials Science and Engineering and director of the Rensselaer Nanotechnology Center.)
Growing nano springs and rods -- Mechanical devices on the nanoscale could be as important as nanoelectronics, but a number of challenges need to be overcome before these systems can be realized. For example, in growing nano springs and rods, a major obstacle is the "fan-out" phenomenon: structures formed with a smaller diameter at the bottom than at the top, rather than growing uniformly. Rensselaer researchers have developed a method to overcome this problem, which they believe could lead to nanoscale devices that are hard to make with current production techniques. The researchers envision a wide range of applications for these devices, including much more efficient light emitters and solar cells, extremely sensitive chemical and biological sensors, and super-high-density three-dimensional magnetic memory.
(Ra19.4, Thursday, Dec. 1, 2:45 p.m., Room 207, Hynes, presented by Dexian Ye, a graduate student in physics at Rensselaer. The principle investigator is Toh-Ming Lu, the R.P. Baker Distinguished Professor of Physics at Rensselaer and recipient of the 2004 Materials Research Society Medal.)
Portable terahertz detection -- T-rays are the next wave in imaging and sensing technology. Based on the terahertz (THz) region of the electromagnetic spectrum, T-rays offer more than just images: they can provide valuable spectroscopic information about the composition of a material. Most THz detectors are cumbersome and can only be operated at very low temperatures, but an international team led by Rensselaer graduate student Dmitry Veksler has developed a portable, room-temperature detector that is orders of magnitude more sensitive than current technologies. The detector could provide a foundation for a new class of remote sensors with applications in a wide range of fields, from detecting explosives and discovering cancerous tumors to probing distant galaxies.
(EE4.4, Tuesday, Nov. 29, 9:15 a.m., Constitution B, Sheraton, presented by Dmitry Veksler, a graduate student in physics at Rensselaer. The principle investigator is Michael Shur, the Patricia W. and C. Sheldon Roberts '48 Chaired Professor in Solid State Electronics at Rensselaer.)
Note to editors:
Abstracts for these and other Rensselaer presentations are available upon request, as are images and other multimedia. The program for the 2005 MRS Fall Meeting is available in its entirety on the MRS Web site at: http://www.
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