Sulfur Signature in Diamonds Reveals New Facts About Early Earth

A University of Maryland-led team of scientists has discovered that diamonds can be natural time capsules, preserving information about the cycling of sulfur between Earth's crust, atmosphere and mantle some 3 billion years ago.

The findings are the latest demonstration that some of Earth's oldest rocks contain "isotopic signatures"--distinctive forms of elements like sulfur and oxygen that can reveal information about many previously unknowable aspects of Earth's early history, such as the evolution of the atmosphere and the origin of early sulfur-metabolizing life.

Diamonds from this open-pit diamond mine in Botswana, Africa, have yielded a trove of information for Maryland geologists studying Earth's atmospheric conditions billions of years ago. Photo courtesy of Steven Shirey, Carnegie Institute of Washington.

The research by University of Maryland geologist James Farquhar and colleagues at Maryland and several other universities show that diamonds from a region in Botswana, Africa, contain a distinctive ratio of three isotopes of sulfur. The signature presence of this ratio indicates that the sulfur in these diamonds went through a nearly complete geochemical cycle.

According to the researchers, that cycle began some 3 billion years ago when sulfur dioxide and hydrogen sulfide gases were spewed into the atmosphere by an ancient volcano. The sulfur-bearing gases in the early atmosphere reacted with ultraviolet light to produce the signature sulfur isotope in aerosols that floated back to the Earth's surface and were incorporated in ancient sedimentary rocks as sulfides. The tectonic plate containing this sedimentary rock eventually shifted downward beneath another plate into the underlying mantle through a process scientists call subduction. When diamonds formed in the mantle, the sulfides with their signature sulfur isotopes were trapped inside. Later, the diamonds were brought to Earth's surface by volcanic processes and eventually mined.

"These findings have the potential to vastly increase our knowledge of Earth's early history," says Farquhar, an assistant professor of geology who is also affiliated with the Earth Systems Science Interdisciplinary Center. "This study conclusively demonstrates that distinctive isotopic signatures created in the Earth's early atmosphere can be found in ancient rocks from the Earth's surface, and that this signature also can be transported deep into the Earth's mantle."

According to Bos Wing, one of Farquhar's post-doctoral researchers and a co-author of the study, the presence of atmospheric sulfur in the mantle may cause scientists to revise their views about the nature of early Earth's sulfur reservoirs. "We now think there is a missing reservoir for sulfur that once cycled through the atmosphere of ancient Earth. Further research might reveal that this missing reservoir resides deep in the Earth's mantle. Such a finding could, in turn, provide important insights into large-scale geophysical processes that have helped shape the evolution of Earth," Wing says.

Sulfur commonly exists as a combination of several isotopes of the element. A few years ago, Farquhar discovered that the photochemistry of Earth's early atmosphere produced sulfur that had a slightly different ratio for three of these isotopes. Finding sulfur with this ratio of isotopes in diamond or other ancient rocks thus indicates that the sulfur was once in the atmosphere of ancient Earth. --Lee Tune

Building a Better Respirator

Respirator improvements are a central focus of a University of Maryland research initiative. Photo by Jason Quick.

Imagine being a coal miner working in tunnels hundreds of feet below ground, an asbestos abatement worker removing contaminated materials from homes or offices, or a firefighter searching through smoke and flames for injured victims. Your life--and perhaps the lives of others--depends upon your ability to perform your job safely and effectively.

But there's a catch: Your work requires the use of a respirator, which protects you from hazardous fumes and airborne particles, but also can impede your ability to perform some essential functions.

Arthur Johnson, a professor in Maryland's Department of Biological Resources Engineering, has spent years studying the effects of respirators on their wearers. The devices often interfere, he says, with breathing, vision, heat exchange and perhaps most important, communication with others.

"Two individuals wearing respirators standing only 1 meter apart can only understand about half the words spoken if no context is given," says Johnson. "At 9 meters, they can't understand each other at all." Phone conversations, he says, are all but impossible using existing technology.

Johnson, with the help of his graduate students, is working under a two-year contract with the National Institute for Occupational Safety and Health to help make respirators more user-friendly. Part of the work involves developing recommendations that could lead to new certification standards for multipurpose air-purifying helmet respirators.

Eventually Johnson hopes to develop a "smart system respirator" for firefighters that would allow real-time monitoring of their vital signs and physical location within a burning building. --Pam Townsend

A Crowning Achievement in Materials Science

Few parts of the human anatomy work harder day in and day out than a person's teeth. The daily ritual of chewing food involves for most adults hundreds of compressions on surfaces ranging from soft bread to hard candy. It's little surprise, then, that dental crowns--molded tooth replacements made of metal or ceramic--take an inordinate amount of stress, often leading to chipping, cracking or painful breaking of a tooth.

Researchers from the A. James Clark School of Engineering are working to reduce the likelihood of such damage by integrating new, stronger and more comfortable materials into the manufacture of dental crowns. They are also looking at ways to harness the power of computers to improve the design and manufacture of crowns.

The scientists, associate professors Guangming Zhang of the Department of Mechanical Engineering and Isabel Lloyd of the Department of Materials and Nuclear Engineering, are part of a $5.9 million research effort sponsored by the National Institutes of Health to improve the strength and durability of ceramic crowns.

Ceramic crowns, which are favored by dentists and patients over metal ones because of their neutral color and greater comfort, have one weakness--they are brittle, says Zhang, who holds a joint appointment in the university's Institute for Systems Research. "If you have a small crack on the surface, it may grow and weaken the structure of the entire crown," he adds. "And if it breaks, it can be very painful and expensive to replace. So the issue [of durability] is very, very critical."

To improve upon existing crown designs, the Maryland scientists are investigating new ceramic materials that are stronger, lighter and more attractive than conventional materials. They are also studying ways that computer-aided design and manufacture can control micro-scale flaws that are common in man-made crowns while at the same time improve the speed and efficiency of manufacture.

"The techniques that we're looking at, instead of making them one at a time, you could actually do a large number at one time. You could also eliminate some of the human variability," says Lloyd.

The research, being led by an orthodontics professor at New York University with scientists from several universities, the National Institute of Standards and Technology and the private sector, aims to improve crown durability by rethinking the composition and structure of the ceramics as well as the approach to their fabrication.

The latest crown designs involve multiple layers of ceramics: an innermost layer, or "supporting core," that is made of a supple material that mimics natural dentin; a hardened inner core layer to support most of the mechanical stresses; a joining layer to transmit stress from an outer aesthetic veneer layer to the inner core layer; and an aesthetic veneer layer.

Besides improving comfort, the new materials may also help to reduce the amount of time required for crown replacement from about a month to a matter of days. --Daniel Cusick

Assessing the Risk of a Maritime Disaster

The events of Sept. 11, 2001 have brought into sharp focus the need for new safeguards and contingency plans in dealing with homeland security--on land, in the skies and on U.S. waterways. One key area of concern being addressed by Maryland scientists is the maritime transportation of hazardous cargo and its susceptibility to sabotage or other terrorist activity.

Illustration by Jason Quick.

Faculty in the Clark School of Engineering are developing software to help assess the risks of a major explosive event on large tankers carrying hazardous cargo. The research, funded by the Naval Surface Warfare Center in Indian Head, Md., is working to assess the damage that might occur if a supertanker carrying thousands of tons of liquefied natural gas, propane or industrial chemicals were to explode in a busy harbor.

"Almost all of the chemicals we are investigating are shipped in large quantities and do not ordinarily react [in an explosive manner] unless an event triggers an explosion," says Greg Jackson, an assistant professor of mechanical engineering who is an investigator on the project. "Our main focus is on the combustion or detonation of a chemical cloud after a dispersion event, whether the dispersion is by accident or intentional."

Steven Buckley, an assistant professor of mechanical engineering and co-investigator on the project, says commercial software already exists to help risk managers predict the dispersion of chemical clouds. But the scientific models for calculating a secondary explosive event are crude and overly simplified. Where these simplified models fail, Buckley says, is that they anticipate that any chemical cloud released would produce a spherical cloud, and that the ignition point of a secondary explosive event would occur at the center of the cloud.

Maryland engineers are working to bring models more in line with reality--that a chemical dispersion can form a complicated plume under the influence of a crosswind, and that a secondary explosion can have a specific directionality depending on the point of ignition. "We are attempting to bring much more fidelity [to the risk assessment] by developing computationally advanced tools for modeling of the detonation, [and] in particular, the point of ignition," says Jackson. "If you are a harbor master and knew a specific ship were coming into port carrying a specific chemical, then you could use this modeling software to determine where the safest area would be to dock the ship." --Tom Ventsias

Hormone Research Holds Promise for Fighting Obesity

Despite a myriad of fad diets, weight-loss drugs and self-help guidebooks, obesity has reached epidemic proportions in the United States. According to the Centers for Disease Control and Prevention, about 38.8 million American adults meet the classification of obesity. "Obesity is linked to the high-risk diseases--such as hypertension, heart disease, stroke, diabetes and various forms of cancer--that account for a majority of the premature deaths in the United States," says Thomas Castonguay, a nutrition and food science professor at the University of Maryland.

To help people fight obesity and prevent the complications associated with it, Castonguay has focused his research efforts on developing a long-term cure for obesity. "Multi-billion-dollar industries have been built around quick fixes, but until we understand how the physiological control system works we won't be effective in treating and curing obesity," says Castonguay, whose research is sponsored by the Maryland Agricultural Experiment Station.

Castonguay studies the mechanisms that control food intake and body composition to get a better understanding of the disease. One of those mechanisms is leptin--a hormone made by the body's fat cells.

"Leptin functions as a satiety signal--it produces a feeling of fullness and signals the brain to stop eating. If there is a defect, then the signal isn't activated and satiety isn't achieved," explains Castonguay. "But it does more than just signal satiety--my research findings show that leptin also helps regulate and control the body's metabolic system."

In addition to his leptin research, Castonguay is also studying how stress affects the biology of obesity. "Stress hormones also interact with the mechanisms that control food intake," he says. "Obese people have high levels of stress hormones in their system. This exaggerated response increases glucose production, which ultimately turns into fat."

Castonguay says that further research needs to be conducted to better understand the systems that control food intake, but a cure based on genetic technology is a possibility for the future. --Megan Michael

Clark School Breaks Ground with "Smart Building"

Jeong H. Kim Engineering and Applied Science Building.

Consider the Kim Building's windows. Rather than choosing one standard window size and type for the entire complex, designers purposely chose different window types for different rooms so that students can study heat transfer through glass. In other parts of the building, normally hidden joists, insulation, wiring and other materials will be exposed so that students can see how engineering principles apply to building construction. The Kim Building will be wired, too, both inside and out, as students collect data from outdoor sensors that pick up vibrations from motor traffic.

"This building will be home to some of the most exciting and innovative research and educational programs in the nation," says Dean Nariman Farvardin.

The building's namesake, Jeong H. Kim, will be honored at a groundbreaking ceremony. In 1991, Kim was the university's first Ph.D. candidate in reliability engineering. He went on to found Yurie Systems Technology, creator of the "Yurie Box," which significantly reduces the cost of voice and data transmissions over large networks.

Kim has recently returned to Clark School as Professor of the Practice, with joint appointments in two departments: electrical and computer engineering and materials and nuclear engineering.

The 160,000-suare-foot Kim Engineering and Applied Sciences Building should be completed by 2005. For more information about the facility, including a detailed listing of the laboratories and research capabilities that the building will house, go to www.eng.umd.edu/research/kim_building.html.

--Daniel Cusick

UMTV Adds Venue for Maryland Research

Interested viewers across the country can tune in to the latest in University of Maryland research through a new UMTV program called "Researching Maryland."

The half-hour show, which airs locally on Wednesdays at 11:30 a.m. and 8 p.m. and is also available via satellite and Webcast, features research subjects from all of the university's science disciplines. Each show spotlights two faculty members and their research, explaining both the details of the research and the impact the outcomes may have on people's lives. The camera follows the scientists in their laboratories, often showing experiments in progress. Then, "Researching Maryland" host and communication professor Andrew Wolvin interviews the professors in UMTV's College Park studio.

Since the show began airing in the spring of 2002, it has featured research on the brain, genetics, plants and pesticides, traffic control, asteroids and smart guns. Upcoming shows will present innovations in veterinary science, entomology and computer science, among other fields.

"Researching Maryland" is also available via satellite on the Research Channel, which airs programming from a consortium of research universities, including Princeton, Stanford, Duke, MIT and Penn. To access "Researching Maryland" online, visit UMTV's Web site, www.umtv.umd.edu.

--Sofia Kosmetatos

Researchers Piecing Together Puzzle of Magnetic Explosions

Scientists have found new information to help explain an old mystery: how solar flare events involving massive releases of energy can happen over the course of minutes rather than years. Photo courtesy of NASA.

A team of scientists led by University of Maryland physics professor James Drake has found what may be a final piece to a puzzle scientists have been trying to solve for almost 40 years: how magnetic fields produce the explosive releases of energy seen in solar flares, magnetic storms and other powerful cosmic events throughout the universe.

Physicists have long explained magnetic field lines, or force lines, as acting like giant rubber bands that release energy when oppositely directed magnetic field lines come in contact with each other. During this process--known as reconnection--parallel magnetic field lines break and reconnect, forming back-to-back slingshots that release their energy by exploding outwards in opposite directions. Since charged particles are trapped on magnetic field lines, most of the energy in the magnetic field is converted to the flow of ionized particles, or plasma, that is pulled along by the rebounding field lines.

However, classic magnetic reconnection theory has one major problem; it incorrectly predicts a gradual release of energy. Theoretical calculations generally predicted that a solar flare should take years or even decades to release energy, while observations have shown it takes only minutes.

In the Feb. 7, 2003 edition of the journal Science, Drake and his colleagues released findings that for the first time indicate that at least some of this explosive energy happens as the result of plasma turbulence generated during reconnection. Using large-scale computer simulations developed at Maryland, together with data from NASA's Polar satellite, the team found that intense currents of electrons are generated during magnetic reconnection.

These intense currents drive strong turbulence that takes the form of "electron holes," regions where the electron density is depleted. The satellite data from Polar indicate that the magnetosphere is riddled with these holes, which have diameters of up to a mile and travel at speeds in excess of 1,000 miles per second. According to the researchers, the intense electric field associated with these electron holes causes electron scattering that is strong enough to sustain fast reconnection.

"Electron scattering by the electron holes also strongly heats electrons and may therefore ultimately provide an explanation for the surprisingly large amount of energy that is transferred to electrons during reconnection events in the solar corona and the Earth's magnetosphere," says Drake. --Lee Tune

Bioengineering Graduate Program Launched

A graduate program in bioengineering that combines research and education opportunities and leads to a master's or doctoral degree was recently launched in the Clark School of Engineering.

"We want to marry the principles and applications embedded within engineering with the sciences of biology, medicine and health," says William Bentley, the Herbert Rabin Professor of Engineering and director of the bioengineering program. "We believe that developments at the interface of biology and engineering will advance the efficacy of health care by creating new paradigms for the diagnosis of disease and the delivery of new therapeutics."

Faculty members in the Clark School are currently engaged in bioengineering research in such areas as medical diagnostics, signal processing and imaging, cellular and metabolic engineering, vaccine development, biomedical devices and instrumentation. Faculty members work in collaboration with nearby health care facilities, medical schools and biomedical research centers.

Ocean Salinity Provides Clues for El Nino Prediction

University of Maryland scientists have found that measuring the salt content of water at the ocean's surface may help improve predictions of El Nino events.

Using computer modeling of the Earth's oceans, Maryland researchers are helping to predict troublesome El Nino patterns. Photo courtesy of NASA.

When changes in ocean salinity occur, they affect the El Nino event for the next six to 12 months, say ESSIC scientists Joaquim Ballabrera, Tony Busalacchi and Ragu Murtugudde. During this lag time, salinity changes have the potential to modify the layers of the ocean and affect the heat content of the western Pacific Ocean, the region where the unusual atmospheric and oceanic behavior associated with El Nino first develops. "As a result, when changes in ocean saltiness are considered, improvements are found in El Nino forecasts six to 12 months in advance," says lead researcher Ballabrera.

Ballabrera and his colleagues looked at data from 1980 to 1995 on sea surface temperatures, winds, rainfall, evaporation, sea surface height and latent heat, which is the energy released when water vapor condenses into droplets. Using computer models, they performed a series of statistical predictions of the El Nino events for such a period. The results indicate short-term predictions only require monitoring sea surface temperatures, while predictions over a season also require the observation of sea level, which is determined by the combination of salinity and temperature.

"This research illustrates the tremendous potential usefulness of the NASA Aquarius mission's monitoring of the surface salinity of the global ocean," says Busalacchi, the director of ESSIC. Aquarius, which is scheduled for launch during 2006-2007, will provide the first global maps of salt concentration on the ocean surface. --Lee Tune