Technology Bulletin 469

Reversible optical switch could yield rewritable
3-D data storage

A light-activated optical switch under development at the Georgia Institute of Technology could be the basis for a new type of rewritable three-dimensional data storage system. By utilizing "trigger molecules" to induce a phase transition in liquid-crystal materials, the system would write, read, and erase information using different forms of polarized and unpolarized light. Such an optical storage system would offer significant advantages over conventional computer floppy disks, magnetic tape, and compact disks, all of which are two-dimensional media. "Using light for memory applications is only going to be useful if you can do it in three dimensions," notes Dr. Gary B. Schuster, professor of chemistry at Georgia Tech. "If you could write three dimensional holograms optically and read them, you would really have something worthwhile." And because a system using the switches would be optically based, multiple light beams could simultaneously read and write data without interference, thus permitting large amounts of data to be packed into a relatively small space. For more information, visit
http://www.gtri.gatech.edu/rco.asp.

Scientists position individual molecules at room temperature

Scientists at IBM's Zurich Research Laboratory have succeeded in moving and precisely positioning an individual molecule at room temperature using the tip of a scanning tunneling microscope (STM). Researchers chose the 173-atom organic molecule because the STM could easily identify its position and structure, and four hydrocarbon groups act as "legs" that lift the "body" of the molecule from the atomically flat copper surface. Also, the molecule was sticky enough to attach to the STM tip, but didn't jitter at room temperature. The breakthrough is a significant step toward practical "nanoengineering." It could help open the way to fabricating molecules with specific properties and functions, constructing computers of ultimately small size, and even to building minute molecular machines capable of cleaning or repairing nanoscale electronic circuits. For more information, FAX Martin Hug at (+44) 1 724 27 95.

Sunflowers may hold key to cleaning radioactive water

Why would anyone want to grow a field of radioactive sunflowers? And why are the engineers who grew them in a pond one kilometer from the Chernobyl nuclear power plant--a site often called "the most radioactive spot on Earth"--so excited? Because this particular patch of sunflowers marks the first successful field demonstration of using terrestrial plants for removing radionuclides from contaminated water, a process called rhizofiltration. The contamination of soil and ground water by radionuclides is a serious problem in areas impacted by the precipitation and use of nuclear materials, particularly uranium, tritium, cesium, strontium, technetium, and plutonium. Enter the sunflower. "Sunflowers are able to absorb heavy metals while leaving others--such as iron--behind," says Burt Ensley, president of Phytotech, an environmental biotechnology firm based in Monmouth Junction, NJ. At the pond near Chernobyl, a field of sunflowers was used to remove cesium and strontium. After four to eight weeks, engineers removed and analyzed the plants. "While the amount of sunflowers was too small to completely clean the pond of radioactivity," notes Ensley, "the bioaccumulation in the plants showed that 55 kg of dry weight sunflowers could sufficiently clean the pond of cesium-137 and strontium-90." For details, FAX AIChE at (212) 705-8400.

Capacitive memory-cell structure could spur 1-gigabit chips

Researchers at Toshiba's ULSI Research Labs have developed a new memory cell with an innovative trench capacitor structure. The cell brings closer the achievement of dynamic random-access memory chips with capacities of 1 gigabit or more and promises lower manufacturing costs than other memory cells, say company officials. A DRAM cell consists of a capacitor and a transistor. Reducing cell size by using ever-finer submicron processing technologies results in a narrower capacitor. Maintaining sufficient capacitance to hold electrons, and therefore data, requires deepening the capacitor, but manufacturing a narrow and deep enough structure has proved difficult. The trench capacitor of Toshiba's new cell has a unique bottle-shaped structure, which can be fabricated with only minor modifications to current processing technology. The structure is narrow at the neck, but wider in the area which holds the electrons. The company expects to have a commercial 1-gigabit DRAM around the year 2000. For more information, FAX Toshiba at (714) 859-3963.

'Tele-exploration' of the Moon set for 1999

Apair of teleoperated robotic vehicles is scheduled to touch down on the Moon's surface in early 1999. The first privately funded lunar mission is being planned by LunaCorp, Arlington, VA, in partnership with the Robotics Institute at Carnegie Mellon, which is developing the rovers using NASA funding. "The Robotics Institute has already developed autonomous navigation technology for terrestrial vehicles, and we're now working on the challenge of the harsh lunar environment," says William "Red" Whittaker, chief scientist for the institute. Whittaker developed the Dante II volcano-walking robot that used autonomous navigation to descend into Alaska's Mt. Spurr in 1994 (see DN 9/26/94, page 68). The lunar mission will let Earth-bound explorers drive on the Moon by remote control while watching high-definition live video displayed on motion platforms that reproduce the rovers' motion as they dip into craters on the Sea of Tranquility. Autonomous navigation capability will protect the rovers from accidentally veering into trouble due to the 3- to 5-second communications delay in round-trip Earth-Moon radio signals. For details, FAX LunaCorp at (703) 841-9503.

Model aircraft flies solo using satellite navigation

Using a 12-foot model, Stanford University doctoral student Paul Montgomery has shown that an aircraft can take off, fly a specified course, and land automatically without relying on hundreds of thousands of dollars of sophisticated equipment. The aeronautics and astronautics engineer controls his model using only the guts of a typical laptop computer, simple onboard wind speed and direction indicators, and receivers that track signals from global positioning system (GPS) navigation satellites. Low-cost automatically piloted aircraft might replace manned aircraft for aerial photography, crop spraying, and police surveillance. Before a flight, Montgomery programs a laptop computer with the path he wants the aircraft to follow. This information is then downloaded to the onboard computer. After engine start-up, he pushes a single button, and the aircraft takes off, flies the course, and lands unassisted. Montgomery's research is one facet of a program at Stanford designed to develop new GPS applications. Related efforts include a GPS-based system that could assist regional or wide-area aircraft navigation and landing, a pseudo-GPS system for robot navigation on the factory floor, and auto-pilot for farm tractors based on satellite navigation. For more information, FAX Stanford at (415) 725-0247.

Thin film coating may reduce the need for lubricants

Advanced Refractory Technologies Inc. (ART), Buffalo, NY, recently received funding from the U.S. Army to further develop diamond-like nanocomposites for hard, low-friction coatings. Says ART President Keith Blakely, "If successful, the DYLYNcoatings will assist both military and commercial organizations to reduce their use of lubricants and greases for small moving parts." Performance benefits may also include eliminating problems with dirt and other contaminants that compromise the performance of lubricants, adds Blakely. The technology offers a variety of customizable properties, claims ART. Coating characteristics can include physical flexibility, adhesion, wear and thermal-shock resistance, and electrical properties ranging from dielectric to superconductive. Coating thicknesses can range from angstroms to microns, with controllable optical properties. Multi-layer gradient coatings are also possible. For further details, FAX ART at (716) 875-0106.

Next-generation helmet to protect F-22 pilots

When the F-22 next-generation fighter jet is fielded early in the next century, the Air Force pilots who fly it will be protected by a new helmet. The HGU-86/P, which will be stronger, more stable, and offer greater impact resistance, is under development at the Wright-Patterson Air Force Base. The new helmet is built to remain on the pilot's head at 600 knots of estimated air speed--up from 450 knots for the previous helmet--in case of pilot ejections that may occur at aircraft cruising speeds. "In the event of an emergency ejection, pilots face a number of dangers, including head trauma and spinal injuries," says product team leader Dawn McGarvey-Buchwalder. "Our goal was to increase safety without exposing the person to any additional risks." The new helmet fits better and is lighter to reduce fatigue, says Buchwalder. For more information, visit http://ascbbs.wpafb.af.mil .

Active motion control' to come to communications satellites

SatCon Technology Corp., Cambridge, MA, recently received a $1.4 million contract from Hughes Space and Communications Co., El Segundo, CA, to design, build, and beta-test control and electronics technologies for satellites. The lightweight, power-efficient technologies will be applied to communications satellites. Thousands of communications satellites will be deployed to support the growth of the information superhighway. Says SatCon President and CEO David Eisenhaure, "One of the major costs associated with a satellite is its deployment. Launch costs can be as high as $25,000 per pound of payload." Compact, lightweight "active motion control" systems will allow spacecraft to carry more payload, such as the communications or scientific equipment being launched on the satellite--thus reducing overall cost, adds Eisenhaure. The firm also recently received U.S. government contracts for the development of flywheel-type products for uninterruptible power supplies. In addition, SatCon will work with General Motors spin-off Delco Remy America in a joint effort to produce an alternator with 50% greater electrical capacity than current alternators. First-phase units are scheduled for delivery later this year. For more information, FAX SatCon at (617) 661-3373.