Developments to Watch
Edited by Ellen F. Licking
Bionic Lungs Coming?
The simple act of breathing is nearly impossible for roughly 750,000 Americans suffering from severe respiratory ailments such as emphysema and cystic fibrosis. Many patients could be helped by an artificial set of lungs powerful enough to circulate oxygen to the body's tissues while expelling carbon dioxide. However, it has proved extremely difficult to design such a device. Now, Dr. Brack G. Hattler, a surgeon at the University of Pittsburgh, says that he has developed an implantable apparatus that works in cows. Human testing should begin later this year in Europe.
Hattler's device involves a simple catheter to which about a thousand tiny fiber membranes have been attached. A vacuum outside the patient's body pumps pure oxygen into the catheter. When the oxygen reaches the fibers, it is forced out into the bloodstream by a balloon. Carbon dioxide, meanwhile, is absorbed and cleared by the fibers' semipermeable membranes.
Because human lungs are densely packed with small air sacs, the total surface area of a pair of lungs is roughly the size of a tennis court. Hattler's device has about the same surface area as a page of this magazine. Nonetheless, tests on animals indicate that the machine can handle about 50% of a normal lung's function--good enough, says Hattler, to ease the burden on a patient's damaged lungs, giving them a chance to heal.
Mining Electricity
Pundits from New York to California grimly predict that as fuel demand outpaces supply, summer's soaring temperatures will trigger costly blackouts and sharp increases in utility rates. One futuristic solution, weirdly enough, may literally be a lot of hot air.
Houston-based CAES Development Co. has teamed up with researchers from Sandia National Laboratories to design a power plant that generates cheap electricity from compressed air. The 2,700-megawatt facility, which is expected to begin operations in 2003, will eventually generate enough power to light up about 700,000 homes. It will be built in an abandoned limestone mine in Norton, Ohio, about 35 miles south of Cleveland.
To generate its inexpensive power, the CAES plant will run compressors nightly and on weekends, when electricity is relatively cheap. Then, in times of peak demand--weekdays between 6 a.m. and 10 p.m.--air will be released from the 540-acre mine and heated, at a small incremental cost. The hot air would then be forced through a series of turbines to generate power that can be sold back to the utility grid. Construction of the new plant will commence in the fall.
The Body's First Line of Defense against Cancer
Researchers have known for some time that certain drugs can rouse the immune system to fight off cancer. But there has never been proof that the immune system can actually prevent tumors from forming in the first place--until now.
In the Apr. 26 issue of Nature, a team of scientists from the Washington University School of Medicine in St. Louis and the Memorial Sloan-Kettering Cancer Center in New York present some of the strongest evidence to date that the body's natural defenses actually guard against the disease.
To elucidate the role of the immune system, the researchers studied what happened when normal and immuno-compromised mice were injected with huge doses of a chemical carcinogen called MCA. Up to 72% of the immuno-deficient mice rapidly developed cancers. In contrast, only 19% of the normal mice developed tumors. Based on the data, the researchers concluded that lymphocytes and other components of the immune system must work together to kill off malignant cells.
Additional studies indicate how this process might happen. By transplanting tumor cells from one mouse to another, the scientists discovered that the immune system filters out certain types of tumor cells. It then goes on to alter other cells based on what it has learned--a process known as immuno-editing.
By Irene M. Kunii
Knowing When the Satellite Is Running on Empty
Communications satellites must use rocket fuel to maintain the precise positions required to transmit phone signals from, say, San Francisco to New York. To sidestep this problem, telecom companies routinely replace the birds before they run out of fuel. But switching off a satellite prematurely can cost millions in unrealized revenues.
Scientists at Purdue University and Lockheed Martin's Space Systems Co. are using a computer program initially designed to understand soap-bubble formation to keep satellites flying up to a year longer. The program gauges fuel levels more accurately than existing bookkeeping methods, which estimate consumption by tracking the duration of all rocket firings in orbit. The new software instead relies on temperature data.
Because rocket fuel freezes in outer space, all satellites are equipped with small heaters and sensors that monitor fuel temperature. Empty areas heat up faster, so temperature information provides a three-dimensional picture of where fuel is located inside the satellite's tank. Based on that image, it is possible to calculate how much fuel is left.
|
Copyright 2001 , by The McGraw-Hill Companies Inc. All rights reserved.
Printer-Friendly Version
