Technology Bulletin 492

Implant wafer approved for brain cancer treatment

The FDA has approved the first new major brain cancer treatment in more than two decades, and the first treatment ever to deliver chemotherapy directly to the tumor site. The product, a dime-sized polymer wafer that dissolves slowly when placed in the brain, is based on novel polymers developed by MIT Professor Robert S. Langer and colleagues (see Design News, June 6, 1996, page 96). The wafer, called Gliadel, will be made by Guilford Pharmaceuticals Inc., a Baltimore biotechnology company, under license from MIT. The product received FDA approval to treat glioblastoma multiforme (GBM), one of the most deadly of all cancers. GBM progresses rapidly and often can kill a patient within one year. The wafer was tested on 222 patients undergoing surgery for recurrent brain tumors. After six months, the survival rate was 56% for patients with the Gliadel implant versus 36% for the group which did not receive the wafer. As many as eight wafers can be implanted into a GBM tumor cavity after surgery to prevent the rapid recurrence of a new tumor. E-mail Elizabeth A. Thomson at [email protected] or Langer at [email protected] .

Silicone replacement focuses on the medical market

The polyvinyl chloride (PVC) industry's appetite for new products presents endless challenges for chemists. Such a challenge was accepted recently in the development of a silicone replacement for the medical industry. The problem: In specific applications, silicone--along with other polymers--has been identified as over-engineered, adding to product costs. The solution: Flexchem, produced by the Colorite Polymers Co., Ridgefield, NJ. The patent-pending polymer, "a combination of new and improved raw materials, carefully selected additives, and advanced processing aids," can be extruded, injection molded, calendered, or blow molded for specific product applications, according to Colorite's Technical Service Manager Meg Henke. Following months of testing, the product was granted Class VI classification for use in medical applications where the resin comes in contact with the body. Flexcem comes in translucent and color grades. It has a Shore A durometer range of 35 to 65. FAX (201) 941-2665.

On-line system probes corrosion problems

Corrosion costs the electricity generation industry billions of dollars a year in maintenance expenses and power lost during forced outages. For this reason, closely monitoring corrosion in fossil fuel and nuclear power plants proves critical. Traditional monitoring techniques, which involve retrieving numerous water samples and testing them in a lab, are time consuming and indicate only average corrosion levels over long sampling intervals. In contrast, an advanced, on-line Corrosion Product Monitoring System, developed by the Electric Power Research Institute (EPRI) in collaboration with Babcock & Wilcox, and commercialized by DETEX Inc., allows continuous measurement of both particulate and dissolved corrosion products. Sample water flows through a specially designed cell containing a filter that captures the corrosion products. X-ray fluorescence spectroscopy measures the deposited material as it accumulates. Analysis of the material is immediate and continuous. FAX EPRI's Deborah Clark at (415) 855-2900, e-mail [email protected].

New light at end of laser-based technologies tunnel

Scientists at Los Alamos National Laboratory wonder what light through yonder window breaks. The new form of laser light travel could create important new laser-based technologies and "revolutionize" older ones. That's the goal of researchers Zin Miao Zhao, David Funk, Charlie Strauss, Toni Taylor, and Jason Jones. When experimenting with a powerful infrared titanium-sapphire laser, the researchers found that when a light pulse intensity reaches a critical value, the beam focuses itself into a thin filament without the aid of focusing lenses or mirrors. It also perpetuates itself for long distances. They believe that the newly discovered light path works because it is so intense and small. The center of the laser creates a plasma and travels faster through the plasma than light travels in air. The packets of light on the fringe of the center eventually feed into the confluence and the beam becomes self-perpetuating. A unique application of the discovery is its potential use as a powerful laser lightning rod for initiating controlled lightning strikes. E-mail Kathy DeLucas at [email protected].

Ink jet boiling process peaks at 1 billion degrees per second

"The bubble-jet printing process is undoubtedly a significant achievement in design and ingenuity, drawing upon concepts in boiling of liquids, electronics, heat transfer, and fluid mechanics," reports C. Thomas Avedisian, Cornell University professor of mechanical and aerospace engineering. But what Avedisian and his colleagues found surprised even them: In confirming the mechanism by which the process works, they measured the highest recorded heating rate on the smallest surface in a boiling process, almost 1 billion degrees per second. Here's how the process works: Tiny droplets of ink are propelled onto paper from print heads about 60 microns square. These droplets, which form characters or other images, are created and propelled by heating the ink in contact with the printheads so fast that the liquid boils sharply, almost explosively. The vapor bubble squeezes the liquid above it partially through a nozzle. Then the bubble collapses extremely rapidly when the power goes off, pinching off the liquid and forming the droplet. In a commercial product, about 100 of the tiny print heads, or resistors, made of a mixture of tantalum and aluminum, sit on a 1/4-inch silicon chip. The researchers are studying just one of these tiny heaters. E-mail [email protected].

Solar-energy technology targets next-generation satellites

LightPath Technologies Inc., Albuquerque, NM, has received a government-funded subcontract to provide the enabling solar energy technology that will allow satellites to produce their own power more efficiently in low earth orbits. For the project, LightPath will adapt its patented GRADIUM^TM glass, which has exceptional light-bending capabilities, to produce first a glass, and later an acrylic solar "light conduit." The conduit will channel light from a satellite's solar collector to its photovoltaic cells, which will turn the concentrated light into electrical power. Use of the conduit will enable the photovoltaic cells to be static, separate from the solar collector, and thus shielded from damaging radiation. And, because of GRADIUM's light-bending properties, there will need to far less "tracking" and movement will be required by the solar concentrator. FAX (505) 342-1111.

Rotman lens offers compact electronically scanned antenna

Researchers at the Georgia Institute of Technology have designed and built a prototype Rotman lens that operates at millimeter wave frequencies. The prototype is believed to be the first Rotman lens to operate at a frequency as high as 37 GHz. Because it has no moving parts, no phase shifters, and can be implemented in plastic, the electronically scanned device presages an inexpensive, rugged, reliable, and compact alternative to current millimeter wave antenna technologies. The device got its name because of its ability to focus microwave or millimeter wave energy coming from a particular direction by passing the electromagnetic energy through a pair of parallel plates shaped like a lens. Variations of the antenna could be used in a range of military and civilian applications, including landing systems, communications equipment, missile seekers, and automobile collision avoidance systems. E-mail [email protected].

'Revolution' in transit technology has arrived

FUTREX Inc., Charleston, SC, and Battelle, Columbus, OH, have teamed to develop a scaled-down model of the "next generation of elevated trains." The System 21 "Monobeam" allows two-way traffic on a slender guideway through a cantilevered suspension design. Key features of the system include: cost of $20 to $25 million a mile (less than half that of conventional rail systems); transport 12,000 passengers per hour, per direction; components made off site, minimizing disruption during installation; patented switch design that avoids interlocking delays and prevents head-on collisions; and a six-foot-wide monobeam that is less obtrusive than conventional two-track systems. The designers say the system is ideal for cities installing their first mass transit system, locations where extensions to existing systems are needed, and campus environments where medium- to high-capacity people movers would be beneficial. FUTREX is looking for investment partners to construct an operational, full-scale, 1.6-mile prototype for $40 million. E-mail [email protected].

Neutrons analyze coal and cement; detect explosives, drugs

A nonintrusive inspection technique that probes samples with neutrons can analyze the content of coal and cement, and detect explosives and drugs. Developed by researchers at the Oak Ridge National Laboratory and Western Kentucky University, the pulsed fast-thermal neutron analysis system bombards a sample with pulses of fast and slow, or thermal, neutrons. Fast neutrons collide with some atoms, triggering the release of gamma rays. Between pulses, thermal neutrons are captured by other atoms, causing emission of gamma rays. Detectors measure energies of the combined gamma rays, which are unique for each element. Such fingerprints permit accurate determinations of concentrations of hydrogen, carbon, oxygen, nitrogen, chlorine, sulfur, and other elements found in samples. FAX Carolyne Krause at (423) 574-0595.

Electronic surveillance research targets hidden land mines

Using $6 million in U.S. Army research funding channeled through Duke University, investigators at five institutions will evaluate new electronic surveillance measures against concealed land mines that endanger the populations of more than 60 nations. The exploratory innovations will range from a microelectronic chemical-sniffing "nose" and through-the-air ultrasound to ground-shaking seismic waves and unique mathematical and computational aids. For example, Duke will team with Caltech to develop advanced electronic odor sniffing polymer strips--branded a "nose on a chip"--that can identify buried explosives much like specially trained dogs. E-mail [email protected].