Technology Bulletin

Space research shines a light on tumors

Special lighting technology developed for NASA's commercial plant growth experiments in space may help treat cancerous brain tumors in children. The treatment, called photodynamic therapy, uses pinhead-size light emitting diodes (LEDs) developed for the experiments to activate light-sensitive, tumor-treating drugs. The light source, consisting of 144 of the tiny diodes, measures only one-half-inch in diameter--about the size of a small human finger. With its cooling system, the entire light source is the size of a medium suitcase. Dr. Harry Whelan of the Medical College of Milwaukee has obtained FDA approval to use the LED probe to treat children's brain tumors on a trial basis. His therapy involves injecting into the patient's bloodstream a drug call Photofrin II, which attaches to the unwanted tissues and permeates into them, without affecting the surrounding tissues. Dr. Whelan then places the solid-state LED probe near the affected tissue to illuminate the tumor and activate the drug. Once activated by the light, the drug destroys the tumor's cells. E-mail steve.roy@msfc.nasa.gov.

Polymer provides new joint surface in osteoarthritis

A new polyurethane formulation suitable for implanting into a joint using minimally invasive techniques may provide relief for millions of people with osteoarthritis. The research, presented recently at the American College of Rheumatology National Scientific Meeting, indicates that the polymer can provide a smooth surface to restore joints in which the cartilage is degraded. The liquid polymer, under development by Advanced Bio-Surface Inc., Minnetonka, MN, is applied using reaction-injection-molding and arthroscopy to the joint surface and cures within two to five minutes in the body. The material remains workable for up to an hour to reshape the bone area, if required. Once cured, the polymer-modified bone surfaces glide smoothly against each other to reduce the painful effects of osteoarthritis. The patient can regain normal activity within 24 hours. Trials of the procedure are now underway in Norway. FAX Dr. Jeffrey C. Felt at (612) 912-5410.

U.S. helps Russian scientists develop prosthetics

After the horrors of enduring a foot amputation due to disease, accident, or landmine, one learns that a prosthesis doesn't flex with the intricacy of a natural limb and may be uncomfortable. However, a researcher at Sandia National Laboratories has arranged funding for eight scientists at a top Russian nuclear weapons lab, Chelyabinsk-70, to divert their expertise in materials science, stress analysis, mechanical design, and computer simulation, to test and improve a new kind of artificial foot. The design, patented by Tufts University professor Mark Pitkin, is licensed by the Ohio Willow Wood. Co., a maker of prosthetic devices. The foot contains a rolling joint that allows the artificial foot to offer little resistance at the beginning of its motion--when an unimpaired person merely pushes his or her weight forward over the foot--and more at its end, when a biological foot would aid in propelling its owner forward. Bands surround the foot like rubber bands around a cylinder. In addition to their binding properties, the bands allow easy motion in the early phases of a step, and then, as stretched, provide stability, or resistance, just like a natural foot. E-mail mlliebe@sandia.gov.

Carbon coating reported to be near-frictionless

Scientists at the Argonne National Laboratory have developed an ultrahard coating said to be many times slicker than Teflon®. Promising applications for the coating, which the researchers say may have the lowest coefficient of friction of any carbon-based material in the world, include auto parts like turbocharger rotors and fuel-injector components, spacecraft mechanisms, rolling and sliding gear systems, oiless bearings, and ultrahigh vacuum instruments. The material has a coefficient of friction less than 0.001 when measured in a dry nitrogen atmosphere--20 times lower than the previous record holder, molybdenum disulfide. In one test, the material lost just one micron in thickness after five million cycles. It is produced in an "rf plasma chamber," which converts a proprietary gas containing carbon into plasma. Carbon and other elements drift down from the plasma onto a substrate, usually a polished disk of sapphire or steel, where they form the coating. FAX Evelyn Brown at (630) 252- 551.

Ultrafine metal powder production process developed

Using a household blender, a laser, and inexpensive reaction materials, Jogender Singh, an associate professor of materials science and engineering at Pennsylvania State University, showed that he could produce ultrafine silver powder "100 times finer than any now on the market." The powder is said to be purer and more uniform, too. In fact, in the invisible 1 to 100 nanometer range, the individual particles are smaller than a small virus. Singh makes the powder by putting silver nitrate, an inexpensive colorless liquid used in pharmaceuticals, photography, and dyes, in the blender with a reducing agent at room temperature. Next, he whirls the mixture while irradiating it in bursts with the laser. As the laser burst hits the liquid, it creates a tiny "hot spot" where the silver nitrate and reducing agent can react. The result: the tiny particle of silver. Singh can make solid particles, porous particles, composite particles, and even hollow nanotubes of a silver-nickel alloy. The process can produce silver and nickel particles at a rate of 0.5 to 3 grams per minute, faster, Singh says, than any other technique now available, except grinding. Grinding, Singh adds, cannot make particles in the nanometer range. E-mail bah@psu.edu.

Scientists hope to catch the ultimate wave

A network of instruments will soon be placed on the ocean floor, giving scientists a much-needed tool to predict and track tsunamis in real time. Tsunamis--giant seismic sea waves, sometimes reaching as high as a five-story building--can crash against coastal communities, kill thousands of people instantly, and devastate property. They are produced by undersea earthquakes, landslides, or volcanic eruptions. "We cannot now predict what kind of tsunamis form, where they are from, and how to accurately gauge their magnitude," explains Philip L.F. Liu, Cornell University professor of civil and environmental engineering. Liu will join other university researchers in an effort to track the tsunamis. One initiative centers on the use of bottom-pressure recorders (BPRs) and seismic instrument arrays for real-time monitoring to be deployed this year. The instruments will be placed by the National Oceanic and Atmospheric Administration in strategic parts of the Pacific, such as south of the Aleutian Islands chain and along coastal areas of Asia. E-mail bpf2@ cornell.edu.

Material puts a damper on low-frequency sound

Existing sound-absorptive materials generally serve as good barriers for acoustical noise above 500 Hz, but perform poorly at lower frequencies. In fact, few manufacturers provide data for frequencies below 155 Hz. For those that do, attenuation values of about 15 dB at 31.5 Hz represent the practical limits for relatively thin (&0.25 inch) configurations. However, while developing a new-concept earcup for protection from very high levels of environmental noise, two Florida researchers developed a class of materials particularly effective at blocking low-frequency acoustical energy. The result: Gasket Material-41 (GM-41), a high-durometer polyurethane to which the composite technology was first applied. The patented process adapts to a variety of materials, including silicones, rubbers, polyurethanes, and epoxy resins, according to its inventors. In a "by request" test, Toyota Motor Co. compared the material used on its steering column boot to the new-technology material. The GM-41 material remained "acoustically transparent" at the lower frequencies, while an optimized silicone rubber of identical thickness (0.040 inch) tested 20 dB more. With the technology, different materials have been extruded, cast, formed, and blown at laboratory scale. Potential applications range from hearing protection to automotive, building, electronic packaging, and sporting goods. E-mail gcatt@eglin.af.mil.

Composite moves step closer to direct tooling

Helisys Inc. has debuted a durable, highly moisture-resistant composite called LOMComposite LGF 045. According to Helisys President Michael Feygin, the material is six to nine times stronger than LOMPaper, and has demonstrated growth in the Z-axis of less than 0.4% under 90% relative humidity. The composite runs with LOMSlice software on the Laminated Object Manufacture machine, which, Feygin notes, "helps bring rapid prototyping one step closer to direct tooling." The composite consists of a base layer of non-woven, randomly oriented glass fibers mixed with ceramic material secured by a thermoplastic binder. A layer of thermosetting epoxy lines the underside of the material. During lamination, the binder and epoxy diffuse into each other, forming the bond. One Beta tester, Gerald R. Hobson of Hobson & Sons, USA reports, "I think the composite is the next step in making almost overnight (two day) blow molded parts." FAX (310) 891-0626.

Space shuttle to test experimental battery

That drum-beating Energizer Bunny better not look back over its shoulder--something indeed might be gaining on it. That "something" is a compact new power source for low-Earth-orbit satellites that may soon be on the horizon--if Air Force tests aboard the space shuttle are successful. Scientists and engineers at the Air Force Research Laboratory's Space Vehicles Directorate are developing a sodium-sulfur battery cell that they say is lighter, tougher, and more powerful than current state-of-the-art nickel-hydrogen batteries running today's satellites. About the size and shape of a rolling pin, the new battery cell weighs half as much and puts out nearly three times the specific power of nickel-hydrogen technology, or 150W per kilogram of battery weight. Since its composition is sodium-sulfur, it also should cost half as much as its nickel-hydrogen counterpart, due to its simpler design. "There are other battery designs out there, such as lithium ion, which we are looking at," says Lt. Chuck Donet, "however, we think sodium-sulfur is appropriate for low-Earth-orbit applications. It is the only technology that has shown itself to be reliable for long-term used based on existing test results." FAX (505) 846-0423.