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June 2002

The Laboratory
in the News

Commentary by
Bert Weinstein

A Two-Pronged Attack on Bioterrorism

Adaptive Optics Sharpen the View from Earth

Experiments
Re-Create X Rays from Comets

Chemistry—
50 Years of Exploring the Material World

Patents

Awards

 

The Laboratory
in the News

Stroke treatment by wire
A springy plastic wire that changes shape at the flick of a switch could provide a safer treatment for strokes caused by blood clots. Developed by engineers at Livermore, the wire, made from shape-memory polymer, will allow surgeons to remove blood clots from the brain without using potentially dangerous clot-busting drugs.
The shape-changing wire is made from two types of polyurethane bundled into one. One type is harder than the other. Team member Duncan Maitland explains that the wire’s main body is constructed from the softer material, with chunks of the harder material distributed though it.
The wire is first heated to allow both its hard and soft components to become malleable. The end of the wire is then twisted into a coil and cooled, fixing the shape of the coil into the polymer. Next, the wire is reheated but to a lower temperature
than it was initially, so that only the softer part is deformed. The coil is pulled to straighten it and then cooled again to harden it. It becomes too rigid to spring back into the coiled shape. However, when heated again to 60°C, the plastic softens sufficiently for the end of the wire to spring back into a coil.
Maitland and his colleagues have tested their invention by conducting in vitro experiments using pig’s blood. They fixed the wire to the end of an optical fiber and inserted both into a narrow catheter. They speared a clot with the wire, withdrew the catheter, and heated the wire with infrared light transmitted through the fiber. “The wire changed into a coil in a fraction of a second,” says Maitland. It grips the clot from behind, and the clot is pulled out with the wire.
Contact: Duncan Maitland (925) 423-6697 (maitland1@llnl.gov).

New combustion method lowers power plant emissions
Livermore engineers have developed a unique combustion method that combines staged combustion with nitrogen-enriched air to lower power plant pollutant emissions.
The new technology, called staged combustion with nitrogen-enriched air (SCNEA), could help power plants comply with strict Environmental Protection Agency (EPA) requirements for decreasing power plant emissions. “As EPA requirements become tighter and tighter on emissions, most solutions become more difficult and more expensive to implement,” says Larry Fischer, principal investigator for SCNEA. “With our technology, consumers will see cleaner air at a miniscule increase in their utility bills.”
Before concerns about oxides of nitrogen (NO and NO2, often called NOx) and their relationship to photochemical smog and acid rain arose in the late 1980s, power plants typically burned fuel in boilers and furnaces with single-stage combustion using air as the oxidant. Today, NOx emissions are regulated under provisions of the Clean Air Act and its amendments. Those regulations will become tougher by 2005, which means that the technologies used to lower NOx emissions must be improved.
SCNEA lowers NOx emissions with a combustion method that burns fuels in two or more stages. In the first stage, fuel is combusted with nitrogen-enriched air. The fuel remaining after the first stage is combusted in the remaining stage(s) with air or nitrogen-enriched air. This method substantially reduces NOx emissions without significantly reducing power plant efficiency and is applicable to many types of combustion equipment and many types of fuels.
Livermore is working to form a consortium of representatives from the U.S. EPA, utility companies, boiler manufacturers, emission control equipment companies, and a company that produces nitrogen-enriched air to further develop SCNEA. The next stage is a small-scale pilot program.
Contact: Larry Fischer (925) 423-0159 (fischer3@llnl.gov).

Laser communication link completed
A Livermore team has completed a 28-kilometer, high-capacity laser communication link between the Laboratory and Mount Diablo. “This represents one of the longest terrestrial high-capacity air-optics links in existence,” says Tony Ruggiero, principal investigator on the project to develop an optical wireless testbed for evaluating new laser communication technologies.
Laser communication consists of an optical system in which information is encoded on a laser beam and transmitted to a receiver telescope. Functionally similar to radiofrequency or microwave communications, lasers use the optical part of the electromagnetic spectrum. The laser communication beam is
not visible or harmful in any way.
The initial Laboratory–Mount Diablo link transmitted data at a single-channel data rate of 2.5 gigabits per second—the equivalent to the transmission of 1,600 conventional T1 data lines, 400 TV channels, or 40,000 simultaneous phone calls.
The experiments are being conducted as part of the Secure Air-Optic Transport and Routing Network (SATRN) program, which is cosponsored by the Nonproliferation, Arms Control, and International Security Directorate and Laboratory Directed Research and Development to provide advanced technologies for long-range laser communications.
Proliferation detection, counterproliferation, arms control, counterterrorism, and warfighting all require the timely and secure communication of information in situations where fiber-optic cable is physically or economically impractical and data requirements exceed radiofrequency or microwave wireless capacity.
Ruggiero says that the next challenge for the SATRN team is transmitting data long distances for longer periods of time to establish a solid baseline for the availability, accessibility, and acceptability of the system’s single-channel long-range link performance.
Contact: Tony Ruggiero (925) 423-1020 (ruggiero1@llnl.gov).


 



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