OAK RIDGE NATIONAL LABORATORY--R&D UPDATES This article also appears in the Oak Ridge National Laboratory Review (Vol. 25, No. 2), a quarterly research and development magazine. If you'd like more information about the research discussed in the article or about the Review, or if you have any helpful comments, drop us a line at: electronic mail, krausech@ornl.gov or pearcejw@ornl.gov; fax, 615/574-1001; phone, 615/574-7183 or 615/574-6774; or mail, ORNL Review, Oak Ridge National Laboratory, 4500-S 6144, Oak Ridge, TN 378312-6144. Thanks for reading the Review. LASER TECHNIQUE DETECTS POLLUTANTS IN FISH Using a laser and a mass spectrometer, ORNL researchers can detect trace pollutants in fish and determine when and where the fish were most exposed to these pollutants. The technique permits scientists to map sources of contamination inexpensively and determine the contamination history of a fish without harming it. ORNL researchers led by Ed Arakawa, leader of the Physics of Solids and Macromolecules Group in the Health and Safety Research Division, have demonstrated the technique using fish scales from striped bass. They believe they have detected polychlorinated biphenyls (PCBs) in the scales of fish three years old or younger. "The scales of a fish have annual growth regions like tree rings," says Arakawa. "Thus, we can determine in which seasons and in which years it was exposed to certain pollutants, such as pesticides, mercury and other heavy metals, and PCBs. "Because we know the local striped bass spend the summer in the Clinch River and the winter in Watts Bar Reservoir and because we can pinpoint when the fish were exposed to certain pollutants, we should be able to determine where contaminants are most concentrated. The fish scales we examined indicated that the fish were exposed to less pollution in the Clinch River than in the Watts Bar Reservoir." The technique includes the use of laser ablation to vaporize different regions of a fish scale, which is composed of calcium and magnesium. An ultraviolet light from an excimer laser knocks off a few atoms from the fish scale and removes electrons from these atoms, making them positively charged ions. These ions form a beam that is pulled by an electric field into a time-of-flight mass spectrometer. Because of the different masses of the ions, they slow down at different rates and are detected at different times, permitting identification of the different elements in the fish scale. One of the "peaks" on the mass spectrometer readouts for recent ORNL experiments indicated the strong presence of chlorine. The source of the chlorine, Arakawa says, is probably PCBs. Chuck Coutant, an expert on the effects of water temperature on fish, proposed the idea of applying the technique to detecting pollutants in the scales of local fish. Coutant and Marshall Adams, both of the Environmental Sciences Division, remove a few scales from striped bass, which are then returned alive to the river, and supply them to Arakawa's group for study. The original analysis was done by Ida Lee, a postdoctoral scientist; physicist Samuel McKenzie; and Arakawa. If additional funding can be obtained, McKenzie and his colleagues will use two ultraviolet lasers to extend the technique to detecting pesticides and heavy metals and measuring pollutant concentrations in fish scales. To determine the accuracy of their technique, they will compare their measurements of pollutants in the outer edge of scales of dead fish from the Savannah River Site with the results of analyses of the total content of each fish. --Carolyn Krause NEW BIOPROCESSING R&D CENTER AT ORNL A Bioprocessing Research and Development Center has been established at ORNL in recognition of the increasing importance of biotechnology to the nation's long-term security and economic prosperity. Bioprocessing uses living organisms to produce new products. Results from ORNL's expanded bioprocessing research and development effort will be transferred to the industrial sector to help make the United States more competitive in the marketplace. Under the new initiative, scientists from ORNL's Chemical Technology Division, supported by the Biology and Environmental Sciences divisions, will develop bioprocesses for energy-related programs and environmental control and will produce a variety of commodity and specialty chemicals. "The hallmark of our efforts, supported by some 25 years of past experience in bioprocessing research, will be to expand interactions with academia, other national laboratories, and industry," says Chuck Scott, senior corporate fellow and newly appointed director of the center. "Transferring bioprocessing technologies to industry will be the ultimate goal of most of our research and development work." ORNL scientists will concentrate on bioprocessing systems that can economically produce fuels and chemicals from fossil materials and renewable feedstocks, including recycled waste material such as paper. Researchers also will develop bioprocessing systems to remove and degrade pollutants. Funding for the center comes from the Department of Energy. Other government agencies benefiting from ORNL's contributions will include the Department of Defense and the Environmental Protection Agency, which need advanced techniques for environmental control technology and waste recycling; the National Institutes of Health, which can use advanced processing techniques to produce therapeutic agents; and the Department of Agriculture, which seeks processes for the small-scale conversion of surplus and waste agricultural products. ORNL has established an interlaboratory initiative for bioprocessing research and development with Argonne National Laboratory in Argonne, Illinois; the Idaho National Engineering Laboratory in Idaho Falls, Idaho; and the National Renewable Energy Laboratory in Golden, Colorado. Laboratory scientists will also collaborate with several university laboratories, including the Center for Environmental Biotechnology at the University of Tennessee in Knoxville. ORNL's achievements in biotechnology over the years include (1) creating advanced techniques for producing liquid and gaseous biofuels to provide alternatives for meeting future energy demands, (2) developing bioreactor systems for producing ethanol and other chemicals, (3) removing nitrates and phenols from industrial wastewaters using microorganisms, and (4) using biological agents to remove hazardous material from polluted soil and groundwater. Funding for programs within the Bioprocessing Research and Development Center is being provided by several DOE offices, including the Office of Energy Research, the Office of Technical Coordination, the Office of Fossil Energy, and the Office of Industrial Technologies. --Brian Daly OFF-THE-WALL IDEA FOR STRUCTURAL EVALUATION Nondestructive evaluation (NDE) of structures, such as walls, bridges, and overpasses, is used to determine how much they deteriorate as they age. Traditionally, techniques such as ultrasonics or radiography have been employed for NDE; however, the limitations of these techniques make them unsuitable for many situations. Ultrasonic systems can measure the depth or thickness of some materials with high precision, but they require a smooth surface through which to pass sound waves. Radiography using X rays or isotope sources is slow, requires the structure to be unoccupied, and requires access to both sides of the wall. Infrared thermography and ground-penetrating radar have also been applied to NDE, but their drawbacks are low resolution and high cost. When a group at the Oak Ridge Y-12 Plant began looking for an NDE technique to examine the condition of the hollow clay tile block walls of some of Y-12's older buildings, Don Bible, Carl Sohns, Richard Crutcher, and Randal Maddox, all of ORNL's Instrumentation and Controls Division, came up with the idea of using a low-power microwave probe to do the job. "DOE officials were concerned about the potential effect of an earthquake on these walls," Bible says. "They knew how the walls were supposed to have been built, and they knew they weren't always built that way. They needed a nondestructive way of getting an internal picture of the walls to locate irregularities. As a result, we began to develop a portable microwave diagnostic probe. "At first, we tested mockup walls with sophisticated lab equipment and various microwave frequencies. Then we came up with the idea of transmitting a simple reference signal into the wall at an angle and comparing the wave characteristics of the signal going in with those of the reflected signal coming out." The microwave signal transmitted into the structure is partially reflected by different layers of materials or irregularities, giving a composite reflection that contains information about each internal layer. This composite signal is considered the "signature" of the structure under test. "Standard" signatures are obtained from structures of known composition that are in good condition. When the signature of the test structure matches the standard signature, the structure is considered normal. A test signature that differs significantly from the standard may indicate irregularities in composition or it may be a sign of structural deterioration. By varying system parameters, such as the frequency of the microwaves or the separation between transmitting and receiving horns, the system can be customized for a wide variety of structures. A more rigorous challenge for the microwave probe was a test wall built at the K-25 Site. "The K-25 wall incorporated a lot of irregularities," Bible says. "They filled some blocks with mortar and stuffed paper or rubber gloves into others--anything they could think of that workers might have done while building the walls at Y-12. That's when we decided to use a computer to compare test signatures with an entire set of standard signatures representing a range of possible wall characteristics." Once tuned for a particular structure, the simple readout eliminates problems of interpretation and allows large areas of a structure to be rapidly examined. Eventually, Bible hopes to incorporate the entire system into a simple, hand-held unit that can be used by individuals with a minimum of training and will display the results of its analysis on a liquid crystal display screen. The probe can also be used for inspection of building foundations, concrete walls, bridge pillars, and road surfaces and for the location of hidden polyvinylchloride pipes that elude metal detectors. Bible expects that this inexpensive, easy-to-use probe would benefit agencies charged with inspecting and maintaining the nation's infrastructure, allowing limited funds to be used on structures most in need of repair. --Jim Pearce STUDYING SNAILS AND STREAM HEALTH A type of snail that is abundant in most streams in east Tennessee is noticeably absent in contaminated Oak Ridge streams, indicating a significant level of pollution. Such a snail could serve as a sensitive indicator of and contributor to improved water quality in Oak Ridge streams as remediation programs take effect. These are two conclusions of a recent study by Walter Hill, a research associate in the University of Tennessee's Graduate Program in Ecology, and Arthur Stewart of ORNL's Environmental Sciences Division. These stream ecologists have focused on snails of the family Pleuroceridae and of the genus Elimia, which are present in large numbers in freshwater habitats. Such snails are particularly useful as indicators of the presence of contamination. Elimia snail studies have been funded by Oak Ridge biological monitoring and abatement programs set up to assess the impacts of pollutants on stream life. These programs are required by the National Pollution Discharge Elimination System permits issued to Department of Energy facilities, including those on the Oak Ridge Reservation. In their paper "Grazers, Periphyton and Toxicant Movement in Streams," Hill and Stewart report that Elimia have probably been eliminated from Oak Ridge streams because of pollutants such as polychlorinated biphenyls (PCBs), heavy metals (mercury, cadmium, and chromium), chlorinated drinking water, and once-through cooling water discharges. The absence of Elimia, the scientists add, not only makes it difficult to study the indirect biological effects of contamination but may also lead to an increased accumulation of contaminants in fish and other animals higher in the food web. The ecologists have used Elimia to study growth rates in three streams near ORNL and plan to transfer individually tagged snails to polluted ORNL streams to determine whether decontamination efforts have been successful. "Elimia is the dominant invertebrate in many uncontaminated streams in eastern Tennessee," says Hill. "Several thousand snails can be found per square meter. This snail owes its dominance partly to its thick shell, which protects it from scouring floods and predators such as crayfish and fish." This type of snail, Stewart says, is well suited for studying the biological effects of toxic materials in streams. It can live in a stream as long as 10 years, permitting extended studies of aquatic conditions. It is sensitive to various toxic substances, and its response can be measured. For example, it responds to toxicants by eating less (reduced feeding rate) and by dispersing in a certain pattern. "Elimia tend to move upstream when water quality is good," Stewart says, "and downstream when water quality is degraded. Because of the large size of the snail, we can determine its rate and direction of movement remotely with a video time-lapse recording." In addition to helping scientists monitor stream health, the snail also may help preserve it. Elimia feed mainly on masses of algae, bacteria, and other organic material that form a slimy film called periphyton. High populations of the snail graze periphyton down to a thin layer, preventing nuisance blooms. Other invertebrate species do not control algal biomass as well as this snail. "By feeding on periphyton," Hill says, "the snails increase the movement of toxic substances downstream. If periphyton is allowed to flourish, the sticky film will take up many toxicants, slowing their net movement downstream. As a result, biologically available concentrations of toxicants in streams with low populations of Elimia snails can remain high, and the toxicants enter the food web more easily." A recent study showed that the concentrations of mercury, cadmium, and chromium in East Fork Poplar Creek are many times higher in the creek's periphyton than in the water itself. The creek receives discharges from the Y-12 Plant, a nuclear weapons production facility in Oak Ridge. "The absence of this snail in Oak Ridge streams," Hill says, "probably increases the movement of toxicants into stream food webs. This effect results from the expansion of the periphyton biomass, which accumulates contaminants in greater quantities the more it grows. Soft-bodied grazers that feed on periphyton become more abundant and further concentrate the pollutants, which move into the food web because these species make a good food for fish." Hill and Stewart see the Elimia snail as an example of a sensitive key species whose removal will amplify pollution effects. "As ecotoxicologists," Hill says, "our challenge is to understand and predict the ecological consequences of both direct and indirect effects of pollution." --Carolyn Krause ORNL CONTRIBUTES TO WETLAND MANAGEMENT To help the nation monitor gains and losses in its wetlands, ORNL is playing an important role in designing a program to measure changes in coastal land cover--marshes, swamps, forests, farms, and urban areas--and to provide reliable data on these changes. Two researchers in the Computing and Telecommunications Division at ORNL are working with the National Marine Fisheries Service to develop the CoastWatch Change Analysis Program (C-CAP). Since the early 1980s Jerome Dobson, a senior research staff member, and Edward Bright, a geographic information analyst, have been developing the program, which is supported by the National Oceanic and Atmospheric Administration (NOAA). A recent proposal to change federal policy to open once-protected wetlands to development angered some environmentalists. The controversy hinged on questions on the definition of wetlands, the role they play in the environment, and the wetland area lost to development or natural changes. Wetlands are those areas of the landscape where land and water meet. They help to control flooding, purify water, and provide an important habitat for fish and wildlife. "The pressure to protect wetlands has been growing in concert with the environmental movement," Dobson said. "As a result, several agencies are supporting a national effort to map land cover and detect wetland gains and losses." Mapping will be done with the aid of geographic information systems, satellite and aerial data, and various ground-based data bases. Dobson said the greatest challenge lies in the sheer size of the effort. "Detecting changes in small areas can be accomplished by making image-to-image comparisons, but detecting changes for areas that cover hundreds or thousands of square kilometers is more difficult," he said. To obtain accurate comparisons, C-CAP researchers first had to develop a consistent method of categorizing land cover (e.g., agree where marshes end and grasslands begin). In September, NOAA, the U.S. Fish and Wildlife Service, the U.S. Geological Survey, and the Environmental Protection Agency agreed on a standardized classification scheme for defining categories of land cover. For each area being monitored, current and earlier satellite scenes must be selected, and careful attention must be given to cloud cover, tidal stage, and vegetative season. Training samples containing areas of known land cover are selected with the help of wetlands ecologists and regional specialists and are then matched with patterns of light reflected from the known area, as identified through remote sensing by satellites. Satellite images consist of 30-m2 rectangles called pixels; data for each pixel indicate the amounts and wavelengths of light reflected from the surface. The type of land cover in each pixel can be determined through statistical analysis comparing unknown pixels with the training samples, Dobson said. "This way we can detect, for example, whether we're looking at an urban area or an agricultural area." He explained that multiple samples of each area are selected to represent each land-cover classification. Then the classified land cover is graphically overlaid on a map. After initial classifications have been made, the researchers begin tests for reasonableness and consistency. These are accomplished by comparing selected areas with other wetlands data sources and by investigating the appearance of unlikely pixels, such as urban pixels showing up in areas where cities are not known to exist, he explained. "Once we're satisfied with the results for each current scene, we add adjacent scenes to create a single regional data base," Dobson said. "Then we repeat the entire process for the earlier time period based on the same ground control points." He said the process of detecting changes between the two scenes consists of a pixel-by-pixel comparison and the creation of a matrix for recording the changes. Dobson said no literature previously existed on how to assess error levels for changes from one time period to another. "We brought in the top error-estimation specialists, who came up with a new and clever solution that involved focusing first on the area and then on the classification," he said. Although national in scope, C-CAP will be administered as a series of regional efforts with help from state governments and universities. Candidates include Chesapeake Bay, Galveston Bay, Tampa Bay, coastal South Carolina, North Carolina, and Rhode Island. "Selected regions will be monitored every five years, except for areas that have experienced environmental disasters or rapid population growth," he said. "Those will be monitored more frequently." Dobson believes the methods and technology developed for C-CAP are the same as those needed for global environmental monitoring and modeling. "The same protocols developed for C-CAPand the care taken in its development are needed for monitoring such problems as deforestation and desertification. The consistent land-cover classifications are especially important to global monitoring, where we encounter very subtle gradients from temperate to tropical vegetative species," Dobson said. "Also, if sea levels begin to rise, the most sensitive indication of these changes will be differences in coastal vegetation." Accuracy assessments for C-CAP will soon be completed, and Dobson said initial results have been encouraging. "If the results are as good as we expect them to be, C-CAP will provide more than just an effective measurement of changes in coastal wetlands. It will also be an effective tool for analyzing public policy and practices to ensure valuable U.S. wetlands are protected, and it could provide environmental analysts with the means to monitor changes in global environmental conditions." --Karen Bowdle WIRELESS ROBOTS IN HOT CELLS Robots can now move freely in a highly radioactive environment too hazardous for humans, thanks to a new method of wireless communication developed at ORNL. With this invention, engineers in ORNL's Instrumentation and Controls Division have made it possible for untethered robots to operate freely in hot cells used for reprocessing nuclear fuel. Until recently, wireless communication in large-volume hot cells had been considered impossible because the metal walls of the cell cause electromagnetic echoes, or reflections, that confuse robots. The new method employs directional radio waves of very high frequency to reduce the reflections to an acceptable level. It also eliminates damaged and tangled robot wires. ORNL engineers have tested the new concept by constructing a Transportable Reflecting Environment Communication System (TRECS). The radio computer system sends signals to the robot's computer, enabling it to perform duties within a cell about the size of a football field. TRECS' electronics are designed to withstand temperatures up to 60øC (140øF) and doses of gamma radiation up to one million rads (200 rads is considered lethal to humans). Although relatively maintenance-free, the system is designed modularly to facilitate any needed remote maintenance. Use of this system will eliminate the large cable bundles that would otherwise be required between the walls of the cells and the operating robots. "TRECS has been fully developed and tested and is ready for commercialization," says Steve Schrock of ORNL's Robotics and Process Systems Division. "We expect the system could be adopted for use in hot cells toward the end of this decade." As part of a DOE cooperative agreement with the French Commissariat a l'Energie Atomique (CEA), French researchers recently tested the TRECS on robotic equipment installed in metal-lined facilities in France. Shrock said the testing was "very successful." --Brian Daly ORNL PRODUCES A NEW BATCH OF RESEARCH ISOTOPES A campaign to produce isotopes of transuranic elements for use in research at DOE laboratories and at other scientific facilities has been successfully completed at ORNL's Radiochemical Engineering Development Center (REDC). This was the first group of such target isotopes processed since operations resumed in early 1990 at the Laboratory's High Flux Isotope Reactor (HFIR) following a three-year shutdown for procedural reviews. The REDC is the production, storage, and distribution center for DOE's heavy-element research program. "It is the world's premier facility for such work and the only outlet for many of the heavy elements," said Bob Wham, REDC manager. "To continue advancing our knowledge of heavy elements, there must be basic research. And this center is the ground floor for that basic research." Transuranic elements, which are called heavy elements because of their high atomic weight, do not occur naturally on the earth. They are artificially produced by bombarding the nuclei of elements such as americium and curium with neutrons. At ORNL, such radioactive isotopes are produced in the HFIR. "We have an abundance of requests from the research community for these ORNL-produced elements," Wham said, adding that the temporary shutdown of the HFIR had created somewhat of a backlog. "Laboratories and other facilities that depend on us to supply the material for their research were anxious for us to be back in business." However, the interim period of the HFIR shutdown was not a time of idleness for the REDC, according to Wham. "The HFIR shutdown actually allowed us time to upgrade our system and to hone our operation so that we can continue to accomplish the goals of our campaigns safely and in compliance with regulations." Uses for the heavy elements produced during the latest ORNL campaign range from studies in nuclear physics to cancer research. One transuranic element that has multiple applications is californium. The Food and Drug Administration proposes using californium-252 for determining the presence and concentration of sodium in food. The isotope can be used for the simultaneous detection in food of toxic heavy metals, such as arsenic or mercury. Californium is also part of a technique now being used at several major airports in the United States and Europe to detect hidden explosives in air passengers' luggage. Because it fissions spontaneously and emits neutrons, californium is used by universities as a "substitute reactor." Wham said that students using the element learn how to develop reactor instrumentation and to analyze the spectrum associated with fission without requiring an actual nuclear reactor. The REDC is operated for production 24 hours a day by members of ORNL's Chemical Technology Division and support personnel from other divisions. --Wayne Scarbrough GLOBAL CO2 EMISSIONS RISE AT A LOWER RATE Global carbon dioxide (CO2) emissions from industrial sources continue to rise but at a lower growth rate than in recent years. According to a special issue of CDIAC Communications commemorating the 10th anniversary of ORNL's Carbon Dioxide Information and Analysis Center (CDIAC), the 1989 estimate for global emissions of carbon represents a 1.2% growth over the 1988 value, "a notable drop from growth rates of the past several years." The 1989 value for global CO2 emissions from fossil-fuel consumption, cement manufacturing, and gas flaring is 5.97 gigatons (thousand million metric tons), compared with 5.90 gigatons for 1988. Emissions from the use of natural gas and other gas fuels and from cement production contributed less than 4% to the total carbon emissions for 1989, which was the sixth consecutive year that global CO2 emissions have increased. In commenting on CDIAC's 10th anniversary, Mike Farrell, former director of the center, writes that, in 1982, he believed that "climate change research was going to be highly theoretical and an area that would never draw much attention from the public." Ten years later, Farrell notes, "global change is the environmental problem of the 1990s and beyond." In fact, Farrell, Paul Kanciruk, and David Reichle, all of ORNL, presented papers at the world's largest conference, the United Nations Conference on Environment and Development (the so-called Earth Summit) in June 1992 in Rio de Janeiro, Brazil. CDIAC is a data management and distribution center. It develops, collates, and provides extensive quality-assurance audits on data bases that are critical to understanding global change. Future initiatives include developing interactive data-analysis systems using a network of computers dispersed throughout the world. According to Farrell, recent statements by Allan Bromley, President Bush's science advisor, and the establishment of the Interagency Working Group on Data Management for Global Change under the Committee on Earth and Environmental Sciences umbrella suggest that issues in data management are now "recognized as equally important in understanding global change as the research that produces the data." --Carolyn Krause BROADBAND ABSORBER LEAVES OPTICAL SYSTEMS IN THE DARK In precision optical systems, such as telescopes, camera lenses, and test equipment, stray reflected light degrades optical performance. Researchers minimize this light by using optically black (nonreflective) surfaces, such as liners, baffles, and beam stops. Unfortunately, the most common methods of creating optically black surfaces--etching, coating, and anodization (an electrochemical process that produces a layer of oxide on metal surfaces)--all have shortcomings that restrict their usefulness. Etching decreases reflectivity, but only if the wavelength of the light is smaller than the etched surface features. Anodized and coated materials are also effective optical absorbers, but their light-absorbing surfaces are easily damaged. Anodized beryllium, among the most widely used material for optical absorbers, is too reflective to be used at certain wavelengths, and because beryllium can be toxic, precautions increase processing costs. To get around these shortcomings, Bob Lauf of ORNL's Metals and Ceramics (M&C) Division and Roland Seals of the Oak Ridge Y-12 Plant's Development Division became interested in creating an absorber that would perform over a broad band of wavelengths and be durable enough to withstand normal handling. They decided to study the feasibility of creating such a broadband absorber using a composite material known as carbon-bonded carbon fiber (CBCF). CBCF, used commercially as a high-temperature furnace insulator, has also been manufactured by other M&C personnel for use as thermal insulation for radioisotope thermoelectric generators aboard the National Aeronautics and Space Administration's space probe, Ulysses. The material is made by mixing a water-based slurry of chopped carbon fibers and a resin binder. The slurry is vacuum-molded, dried, and then heated slowly to melt the resin and bind the fibers together. Finally, the resin is converted to carbon at high temperatures, and the component is machined to its final shape. Lauf and Seals persuaded Clyde Hamby of the M&C Division to formulate several batches of CBFC with less fiber and more binder, hoping to create a material that was more rugged than standard CBFC. After some tinkering with the recipe, Lauf and Seals found what they were looking for. The resulting material is uniquely well suited for use as an optical absorber for a variety of reasons. First, because CBCF is a bulk material rather than a surface enhancement or coating, it is optically black throughout, making it immune to surface damage. Another M&C co-worker, Al Akerman, demonstrated that CBFC can be sanded and machined without losing its light-absorbing properties. It is unaffected by small variations in processing, unlike anodized or vapor-deposited coatings, which are highly sensitive to process variables. In addition, it absorbs light over a much wider spectrum than many standard optical absorbers--up to at least 50 microns, compared with 10 microns for etched beryllium. Also, it is lightweight, easily fabricated into almost any shape, and, because of its low atomic weight, it is highly resistant to radiation and thermal damage. "This is an amazing material," says Lauf. "You can make a big billet of CBCF, machine it to any shape you want, and it's automatically optically black. It's much more robust than any of the competing products. You can cut it, file it, or even machine shapes into its surface. Also, because it's carbon, it's not toxic. And it's pretty cheap as high-tech materials go." CBCF can be used wherever low reflectivity is needed over a wide range of optical wavelengths. Examples include liners and baffles for telescopes and beam stops for laser equipment. In addition, CBCF can be coated with metal and used as a diffuse-reflectivity standard for calibration and testing of optical equipment. The compound is ideally suited for use in standards and other components that must be handled frequently because its optical properties are not affected by surface contact. For applications in which greater structural strength is needed, CBCF can easily be bonded to a dense graphite backing. Or, if a combination of reflection and absorption is needed, such as in advanced annular baffle systems used to minimize unwanted light in telescopes, it can be attached to sheets of reflective metal. "We'd like to develop other spin-offs of this technology, " says Lauf. "Using CBCF as an optical absorber is only the first." --Jim Pearce (keywords: pollutants, lasers, bioprocessing, microwave probe, wetland management, robotics, isotopes, carbon dioxide, optical absorbers) ------------------------------------------------------------------------ Please send inquiries or comments about this gopher to the mail address: gopher@gopher.ornl.gov Date Posted: 2/7/94 (ktb)