Dartmouth Engineer

Cellulosic Ethanol Breakthrough

Lee Lynd, Thayer’s Paul E. and Joan H. Queneau Distinguished Professor in Environmental Engineering Design, and his team have engineered a cellulose-dissolving bacterium that could lead to cheaper and more sustainable ethanol production. In this country, fuel ethanol is produced from corn. Producing ethanol from cellulosic feedstocks — such as wood, grass, and various residues — rather than food sources has obvious advantages. But a key constraint to the feasibility of ethanol production from cellulose is the cost of cellulase, the enzymes that convert fibrous biomass into sugars that can be fermented.

Currently, ethanol production also utilizes yeast, which grows at moderate temperatures of 30 to 35 degrees C. In a major breakthrough, Lynd’s team has engineered a new bacterium, strain ALK2, that grows at 50 to 60 degrees C. — a temperature that speeds the breakdown of cellulose — and ferments all sugars in the biomass into ethanol. Under controlled conditions, Lynd reports, the amount of cellulase needed to break down cellulosic feedstocks is slashed in half when ALK2 is used in place of yeast.

“This work shows that a new class of potentially important organisms can be engineered to produce ethanol as the only fermentation product,” says Lynd, who is chief scientific officer and co-founder of Mascoma Corp., a leading developer of cellulosic biofuel technology. “This opens up new and exciting possibilities going forward,” he adds, noting that Mascoma plans to test strain ALK2 in its pilot plant in Rome N.Y.

Lynd and his team published their findings on the ALK2 thermophilic bacteria online in the journal Proceedings of the National Academy of Science during the week of September 8, 2008.

—Elizabeth Kelsey

Therapy in Space

Cramped quarters. Life-or-death decisions. Missions that last months or years. These are just some of the psychological stressors astronauts face. To help them cope, Thayer adjunct professor Dr. Jay Buckey Jr., a former astronaut, has teamed with Dr. James Cartreine of Harvard Medical School and other researchers with the National Space Biomedical Research Institute to develop an interactive, multimedia program called the Virtual Space Station. According to Buckey, the multimedia aspect of the program, which enters clinical trials this winter, provides an important emotional component. “Just like a good movie, it will draw you in and let you respond to the characters,” he says.

Dr. Jay Buckey Jr. flew on the Columbia space shuttle. Photograph courtesy of NASA.

While participating in NASA’s Neurolab mission on the Space Shuttle Columbia in 1998, Buckey became interested in addressing potential barriers to flights to Mars or other long-duration missions. Psychological stressors, such as interpersonal conflict or depression, can destroy missions if they are not handled well, he says. With the Virtual Space Station, on-screen psychologists lead users through lectures, exercises, interactive simulations, and programmed interventions. Astronauts can take diagnostic tests, work through simulations, and practice problem-solving strategies. The system, which runs on any laptop, will be accessible anytime, anywhere. Currently, space-based astronauts can only consult with therapists on the ground when communication links are available.

The Virtual Space Station also has practical applications here on earth. Doctors’ offices, schools, oil rigs, and other remote locations would benefit from the portable therapy. Buckey hopes the program will enable more people to receive assistance for conditions that are sometimes stigmatized. “Often people are more comfortable working with a computer for these kinds of problems,” he says. “With this program, we hope that people will seek help earlier, rather than letting the situation become worse.”

—Elizabeth Kelsey

Fighting Decompression Sickness in Space

Another space project of Buckey’s that has earth-bound applications is his work with decompression sickness (DCS). Because current spacecraft and suit designs require astronauts to move through different pressure environments, the prevention of DCS is a priority for spacewalks. When humans move from areas of high pressure to low, nitrogen can be released in the body in the form of bubbles. Buckey and Creare Inc. are currently developing a dual-frequency instrument to detect and size nitrogen bubbles in body tissue. The instrument uses two frequencies of ultrasound (similar to the frequencies clinical ultrasound machines use) to detect and size bubbles through the chest wall as they move through the heart. The instrument also can detect small, stationary bubbles in tissue — a unique capability. One potential benefit is the ability to detect the earliest stages of DCS and allow for preventative strategies like oxygen pre-breathing and the limiting physical activity at critical times. Further, the instrument can potentially be used in coronary bypass surgery to distinguish between solid and gaseous emboli and in industrial and aviation applications to determine the gas saturation in fluids.

—Elizabeth Kelsey

Power Line De-Icing

Russia and China are taking advantage of Professor Victor Petrenko’s de-icing system for power lines. Both countries have placed orders with Petrenko’s company, Ice Engineering LLC.

Petrenko’s variable resistance cable (VRC) de-icing system switches the electrical resistance of a standard power line from low to high, automatically creating heat to melt ice build-up or keep it from forming in the first place. The system can be implemented for less than a ten percent increase in overall cost and can also be installed as part of regularly scheduled maintenance. “The beauty of the VRC system is that it’s fully customizable and is an affordable addition to the current manufacturing and installation process,” says Ice Engineering vice president Gabriel Martinez.

—Kathryn LoConte

For more photos, visit our Engineering in Medicine and Research and Innovations pages on Flickr.

More Power, Less Money

Charles Sullivan

Thayer Professor Charles Sullivan is working to improve the performance of passive high-frequency power components in order to make power electronics more energy efficient and cheaper to manufacture.

According to Sullivan, the passive components are often the limiting factors in improving the efficiency and lowering the cost of high-frequency electronic power converters. His research targets inefficiencies in the inductors, transformers, and capacitors that handle AC-DC, frequency, and voltage conversions required by electronic devices. For example, the power adaptors that laptop computers use to convert 120-volt AC power to lower voltage DC power lose considerable energy in the form of heat.

High-frequency electronic power converters are often problematic due to their size and weight, says Sullivan. Designers, he says, generally know how to make high-frequency power converters more efficient, but the results can be unwieldy and prohibitively expensive. Thus, efficiency often is sacrificed to make converters affordable. Sullivan maintains that innovation in both the application of new materials and the geometric configuration of circuits will improve the performance and cost of passive power components.

He sees advances in information technology as both a model and means for improving power electronics. “Electronic information handling has made it possible to access efficiently exactly the information we need,” he says. Applying similar techniques to energy processing would “similarly allow us to use exactly the energy we need where and when we need it, with less waste,” he says. “Our goal is to make designing power electronics as easy as designing information electronics, so that we can see the same rapid advances in energy applications as we’ve seen in information applications.”
— Elisabeth McDonnell ’08

Pollution-Detecting Molecules

Thayer Professor Ursula Gibson ’76 and researchers at the University of New Hampshire are collaborating on a new method of monitoring watershed pollution: using molecularly imprinted polymers to detect contaminant molecules. Designed to recognize organic solvents, the polymer films can target a pollutant and generate a signal based on its concentration. An array of such sensors could be used to detect spills and locate their sources.

Gibson’s team is currently developing the polymer coatings and investigating how to arrange them in the most sensitive configuration. Once they accomplish this, they will work on integrating specific coatings into an autonomous sensor package capable of identifying pollutants and reporting their levels for extended periods.
— E.M.

For more photos, visit our Research and Innovations Flickr page.

A­dvances in Ethanol

The nation’s thirst for gasoline alternatives is driving new rounds of investment in Mascoma Corp., the cellulosic biofuel company co-founded in 2005 by Thayer Professors Lee Lynd Th’84 and Charles Wyman. The three-year-old startup recently reached $100 million in equity investment and received commitments for another $100 million in state and federal grants, including a $26-million grant from the U.S. Department of Energy.

Using proprietary microorganisms developed at the company’s laboratories in Lebanon, N.H., Mascoma is pioneering new ways to turn non-food, renewable biomass — including wood, straw, switchgrass, paper pulp, and agricultural wastes — into ethanol and other biofuels. Lynd, recipient of the first Lemelson-MIT Award for Sustainability in 2007, is championing a single-step process for converting cellulose to ethanol — he calls it Consolidated Bioprocessing (CBP) — that is designed to be faster, cheaper, and more efficient than current methods. Mascoma is testing its CBP technology and expects to begin ethanol production later this year at the demonstration plant it is constructing in Rome, N.Y.

Investors in Mascoma, whose corporate office is in Boston, now include Marathon Oil Corp., General Motors, Khosla Ventures, Flagship Ventures, Atlas Venture, General Catalyst Partners, Kleiner Perkins Caufield & Byers, Pinnacle Ventures, and Vantage Point Venture Partners.

For Lynd’s views on the viability of cellulosic ethanol as an alternative to corn-based ethanol, read Answers to the Growing Fuel Debate.

For more photos, visit our Energy Technologies and Sustainability Flickr page.

Antarctica’s Cold Data on Climate Change

Mary Albert, an adjunct professor at Thayer School and senior research engineer at the U.S. Army’s Cold Regions Research and Engineering Lab in Hanover, is the lead U.S. partner on a Norwegian research expedition investigating climate and glaciology in East Antarctica. The project is one of more than 200 encompassed by the International Polar Year (IPY), a research program that began in March 2007 and will continue through March 2009. In late October Albert, chair of the U.S. Committee to the IPY from 2003 to 2005, joined the rest of the team in Queen Maud Land, Antarctica. On November 16 they set off on their traverse of the East Antarctic Plateau.

POLAR EXPRESS Mary Albert, fifth from right, poses with the Norwegian research team before their Antarctic traverse. Photo courtesy of the Norwegian-U.S. Scientific Traverse of East Antarctica

The plateau is part of the vast East Antarctic Ice Sheet. The route for the trek is from Troll Station, a permanent Norwegian research station located halfway between the coast and the plateau, to the United States South Pole Station — a distance of some 1,740 miles. In addition to traveling through previously unsampled areas, the team is revisiting sites investigated in the 1960s. Their objective is to collect ice cores for later analysis and to study the physical and chemical properties of snow and firn (old snow) within shallow snow pits — all to advance our understanding of climate variability within East Antarctica and its role in the global climate system.

To develop historical temperature profiles, the research team will conduct isotopic analysis of the ice and firn cores drilled at different locations on the plateau. Albert is measuring the air permeability, thermal conductivity, density, and microstructures within snow and firn stratigraphy. By comparing these data with those from other expeditions carried out since 1999 under the International Transantarctic Scientific Expedition program (consisting of 21 member countries), the team will be able to map climate history and climate patterns over the past 200-300 years.

At Thayer School Albert acts as thesis advisor to graduate and undergraduate students.

Trek details, including maps, photos, and an expedition diary, are at traverse.npolar.no.

Smart Helmet Detects Brain Trauma

Simbex LLC, founded by adjunct associate engineering professor Richard Greenwald Th’88 and adjunct professor emeritus Robert Dean, recently expanded its head-impact biomechanics testing arena from the athletic field to the battlefield.

Simbex’s HIT System helmet measures impacts to assess brain injury. Photo courtesy of Simbex LLC.

The Head Impact Telemetry (HIT) System™ is a biomechanical feedback system that measures the magnitude and severity of head impacts related to mild traumatic brain injury (mTBI). Sensors installed in the helmet measure and record the linear and rotational acceleration of the head following an impact. The data can be transmitted wirelessly to a laptop computer on the sidelines, which calculates all the key biomechanical elements of impact for later analysis.

The HIT System, incorporated into commercially available Riddell football helmets, has been tested extensively on high school and college football fields. Time magazine hailed it as one of the “Best Inventions of 2007” (see Kudos).

In April, Simbex, in partnership with researchers from Dartmouth Medical School and the athletics departments of Dartmouth, Brown, and Virginia Tech, was awarded a $3.6 million Bioengineering Research Partnership grant from the National Center for Medical Rehabilitation Research at the National Institutes of Health (N.I.H.).

More recently, the U.S. Army asked Simbex to test the technology for use on the battlefield.

The most common mTBIs in the current U.S. wars in Iraq and Afghanistan are those caused by improvised explosive devices (IEDs). IED shock waves travel at around 1,000 feet per second, almost as fast as the speed of sound. Shrapnel bouncing off a helmet can rattle the brain’s soft tissue and cause invisible but permanent damage. Such injuries often go unnoticed until the soldier begins experiencing short-term memory problems or undergoes a change in attitude. The Army has requested technology that can record the biomechanics of head trauma received in combat and provide data for medical staff to quickly analyze the extent of brain injury so that soldiers can get the treatment necessary to return them fit for military or civilian life.

The instrumented combat helmet employs eight accelerometers with high bandwidth so that both high magnitude and high frequency impacts can be recorded. A pressure transducer measures changes caused by shock waves. Should the army decide to implement HIT technology for widescale battlefield use, Simbex will redesign the data collection system to be compatible with existing technologies currently used in army bases, such as hand-held scanners employed by medics in the field.

Simbex also recently received N.I.H. grants for rehabilitation product development, including their fall-risk assessment and fall prevention training system, an in-shoe monitoring system for children with cerebral palsy, and a novel orthopedic implant to improve prosthesis fit and overall comfort and stability for lower-limb amputees.

Over the years, a number of B.E. and M.E.M. students have worked with Simbex engineers to improve design and testing of the different systems; some of those students have gone on to become Simbex employees.

— Ellen Frye

For more photos, visit our Research and Innovations Flickr page.

Process Query System

CYBER-DECEPTION DETECTORS: Berk, left, and Cybenko. Photograph by Joseph Mehling

Gathering information — from network monitors, surveillance cameras, financial records — is easy. Making sense of large quantities of raw data is not.

The Process Query System (PQS), developed by George Cybenko, Dorothy and Walter Gramm Professor of Engineering, employs two tools to solve this challenge: a software framework for categorizing irregularities within a system and algorithms that can provide detailed explanations of those irregularities.

All computer systems are characterized by distinct states, dynamics, and other properties that can be picked up by sensors. Installed into a particular system, PQS quickly reads such data, detects changes or oddities, and infers intent by separating honest errors from potentially deceptive activities.

Perhaps the most useful PQS application to date is in the area of network security. Currently available monitoring tools produce information in quantities that make analysis a formidable task. “PQS closes the gap between gathering a tremendous amount of valuable data and figuring out what the data mean,” says Professor Cybenko.

Other applications for PQS could include scanning credit reports for identity theft or detecting suspicious activity at an international border.

Cybenko and research associate and lecturer Vincent Berk published a paper on PQS in the January 2007 issue of IEEE Computer. The research, a project of Dartmouth’s Institute for Security Technology Studies, is supported in part by funding from the U.S. Department of Homeland Security, Directorate for Science and Technology, and the Department of Defense (DTO, AFRL, and DARPA).

Inductor Efficiency

The efficiency of current power electronics equipment is limited by the typical power loss in high frequency power converters. Doctoral candidate Jennifer Pollock and Professor Charles Sullivan have recently patented a new inductor technology that is likely to become the industry standard for converters used in hybrid vehicles, wind energy systems, photovoltaics, fuel cells, and other applications.

The new technology provides the low DC resistance of a foil-wound inductor without the high AC resistance ordinarily found in such inductors. The result is an inductor that is both smaller and more efficient than inductors currently used in power supplies, inverters, and electric motor controllers. The technology is well suited to newer silicon devices such as Insulated Gate Bipolar Transistor (IGBT) modules, which handle currents in the order of hundreds of amperes with blocking voltages of up to 6000 volts while operating at frequencies over 10 kHz.

Tests in Professor Sullivan’s labs measured the potential energy savings of the new foil-winding technology and found that total winding losses of the new inductor were 17–35% lower than those in conventional solid-wire or litz-wire inductors.

The technology has been licensed by West Coast Magnetics in Stockton, Calif. The company forecasts a global market for inductors using this technology that may reach $2.5 billion by 2015 with the greatest opportunities occurring in the hybrid vehicle market and in power generation for wind and solar power equipment. If the technology is extended into lower power applications such as personal computers, desktop electronic equipment and handheld devices, West Coast Magnetics says that the 2015 global market could exceed $5 billion.

Advances in Breast Cancer Detection

By combining two techniques, magnetic resonance imaging (MRI) and near-infrared optics (NIR), researchers led by Professor Keith Paulsen may have devised a new, potentially more accurate method for diagnosing breast cancer. Their pilot study, demonstrating the feasibility of the concept, was published in the April 15 issue of the journal Optics Letters, published by the Optical Society of America.

MRI produces information on the shape and composition of breast tissue, while NIR measures its blood volume and oxygen saturation. Thus the MRI provides information on the form and the NIR on the function. Together the two techniques create high-resolution functional images of tissue, which can then be compared with tissue that is known to be cancerous.

The pilot study involved a 29-year-old woman with a ductal carcinoma, a common breast cancer. Using the information from a contrast MRI procedure — one MRI done before and one after the contrasting agent gadolinium is injected — the research team pinpointed the region for the NIR. Results showed tissue with high hemoglobin level, low oxygen saturation, and high water content — all indicators of cancerous tissue.

A follow-up study will draw on volunteers who have breast abnormalities and have been recommended for biopsy. Using the MRI/NIR technique on the subjects before and after the biopsy, the researchers will be able to compare their results to the biopsy results.

The Thayer researchers, including Paulsen, Professors Brian Pogue and Shudong Jiang, and Adjunct Professsors Hamid Dehghani and John Weaver, are collaborating with Dartmouth Medical School researchers and Dartmouth-Hitchcock Medical Center clinicians.

-Ellen Frye

For more photos, visit our Research and Innovations and Faculty Flickr pages.

Antibodies from Yeast

Researchers from Thayer School, Dartmouth Medical School, and biotechnology firm GlycoFi recently reported a major advance in protein bioengineering. The team made a breakthrough in using yeast to produce antibodies with human sugar structures. Antibodies are proteins with sugars attached to them.

The team’s latest work shows that antibodies with increased cancer-killing ability can be produced by controlling the sugar structures that are attached to them. The finding is important because antibodies are emerging as a significant class of cancer drugs. This research shows that an antibody with human sugar structures can be produced in the lab. GlycoFi’s approach can be applied to other glycoproteins, a growing class of therapeutic proteins.

The research was published in the February issue of Nature Biotechnology. GlycoFi was founded in 2000 by Thayer School professors Tillman Gerngross and Charles Hutchinson.

The March issue of Nature Biotechnology includes Gern­gross in its shortlist of researchers who have made the most significant contributions to biotechnology in the past 10 years.

— Sue Knapp

Breaking the Ice

Professor Victor Petrenko’s Icenabled™ icemaker may soon freeze old machines out of the $1 billion icemaking business.

Utilizing his pulse electro-thermal de-icing (PETD) technology, the Icenabled icemaker “will be more productive, more space efficient, more energy efficient, more reliable, and will make ice faster and of higher quality than ever before,” he says. “This technology can increase an icemaker’s production capacity by 70 percent while decreasing its energy consumption by up to 30 percent.”

Conventional commercial icemakers, ubiquitous in hotel hallways, restaurants, and hospitals, consume enormous amounts of power. They cycle through a process of cooling to make the ice and heating to release the ice as many as 100 times a day.

An Icenabled icemaker uses PETD to virtually eliminate the heating portion of the cycle. PETD removes the ice instantly using a high-power electric pulse that lasts less than a second. This same technique can also eliminate the need for conventional hot gas defrost systems.

PETD could ultimately transform the entire $40 billion refrigeration and air conditioning industry, which, according to Petrenko, has struggled with the challenge of keeping cold evaporator coils free of frost and ice. PETD has proven its ability to de-ice these coils in seconds using a fraction of the energy required by conventional coil defrosters.

Petrenko and his company, Ice Engineering LLC, are working on several other applications for PETD, including de-icing buildings, bridges, car windshields, airplanes, windmills, ships, and power lines.

— Catharine Lamm

For more photos, visit our Research and Innovations set on Flickr.

Alex Streeter ’03, Th’05 And adjunct associate professor Jim Lever spent two weeks in Greenland during the summer to test Thayer School’s solar-powered “Cool Robot” against the cold realities of extreme climates. Designed to be a mobile platform for conducting scientific experiments in the Arctic and Antarctic, the 165-pound robot performed well. “We demonstrated that the robot can navigate long distances autonomously following a GPS course; drive over rugged terrain and soft snow in excess of what we can expect in Antarctica; operate on solar power so long as the sun lasts; match the power from the different solar panels to the instantaneous demand; and tow more than twice its own weight,” Streeter reported in an online log. The robot has been in development for two years under the leadership of Lever and associate professor Laura Ray.

COOL DUDES: Streeter, left, Lever, and the Cool Robot catch some rays in Greenland. Photograph courtesy of Alex Streeter.

For more photos, visit our Research and Innovations set on Flickr.

Wireless, Wearable Triage Gear

Associate Research Professor Sue McGrath, director of the Emergency Readiness and Response Research Center at Dartmouth’s Institute for Security Technology Studies, is developing a wearable, wireless, mobile communication system that will help medics and emergency teams conduct triage in high-risk situations.

LIFELINE: Professor Sue McGrath’s remote triage information system will aid victims and rescuers. Photograph by Chris Milliman.

Called Artemis (Automated Remote Triage and Emergency Management Information System), the system allows a team of hand-held computers to pass data wirelessly to one another and ultimately back to an emergency command center. Each Artemis unit can be worn on a belt and attached to GPS, vital-sign, or other monitors to gather and transmit critical data.

Last spring McGrath’s team tested a prototype in an emergency training exercise in which rescuers freed an “injured” construction worker from scaffolding beneath Cape Cod’s Bourne Bridge. The system outwitted interference from the concrete and metal in the bridge by bouncing signals between Artemis units, then back to the collector computer. The field trial led the team to improve the wireless networking, user interfaces, and software models. “Our experiments and exercises teach us a great deal about how the system could be used in actual emergency and battlefield conditions,” says McGrath. She predicts that a commercial system could be available in two to four years.

The research is sponsored by the Department of Homeland Security’s Office of Domestic Preparedness and by the U.S. Army Communications and Electronics Command Division.

Taking the Pain Out of Joint Replacements

Nearly half a million total hip and knee replacements are performed annually in the United States. Despite the high success rate of these procedures, an additional 60,000 surgeries are performed each year to replace failed prostheses. By analyzing failed prosthetic joints, the Dartmouth Biomedical Engineering Center for Orthopedics, headed by Professor John Collier, has greatly reduced the incidence of one cause of prosthetic failure, oxidation-related breakage of polyethylene bearings in artificial joints.

But many patients face another problem. The abrasive and adhesive wear of bearings in prostheses can cause microscopic particles of plastic and metal to migrate into the tissue surrounding artificial joints, causing an inflammatory, bone-resorbing reaction known as osteolysis. Collier and his colleagues are collaborating on a new research project to identify the factors that lead to this condition. Subjects will include both patients who have osteolysis and bone resorption and patients who are not experiencing resorption or infection despite loosened artificial joints.

After surgical removal of failed implants, samples of surrounding tissue are examined by pathologists, then sent to the Thayer School researchers to quantify and classify wear particles. By examining physical characteristics of the debris, patterns of wear on the removed prosthetic components, and tissue histology, the team hopes to identify conditions that lead to joint failure. Project goals are improved prosthetic joint design, better surgical techniques, and, ultimately, a decrease in the incidence of osteolysis-related joint failure.

Collier’s team includes pathologist Justin Cates, orthopedist Michael Mayor, Ph.D. candidate Doug Van Citters ’99, Th’03, medical student Derek Jenkins ’02, and undergraduate Katie Muse ’05.

Smart Football Helmets

A lightweight biofeedback system that measures the force of impact football players experience during head-on collisions is being field tested at three colleges this year. Thayer School Adjunct Professor Richard Greenwald, head of Simbex, the West Lebanon, N.H., company that is developing the Head Impact Telemetry System (HIT), says the patented invention can minimize the guesswork coaches apply every time a player goes down from a head-on collision.

HIT sensors embedded inside a football helmet continuously measure the force of blows to the head and wirelessly transmit the information to a compact console on the sidelines. Coaches can view images and graphs detailing the magnitude, location, direction, and duration of each impact.

Data gathered last year from 38 Virginia Tech players indicate that hits to the head have an average force of 40g — 40 times the force of gravity — and that impacts can reach as high as 180g, the kind of force involved in severe car crashes. Studies this year also include players from the University of North Carolina and University of Oklahoma.

While the National Football League has conducted lab research on concussions, Greenwald’s device is the first to measure on-field head impact for a large number of players. “The HIT System allows us to track players’ cumulative history over time,” he says. “And that is important because most researchers believe that cumulative impacts — not just one impact — may be significant in terms of sustaining more concussions and also long-term cognitive deficits.”

Research and development of the HIT System was funded by the National Center for Medical Rehabilitation at the National Institute for Child Health and Development at the National Institutes of Health.

Down Under for Nanotechnology

Two of Professor Ian Baker’s students, James Hanna ’02 and Johnathan Loudis ’05, traveled to Australia in March to use the University of Sydney’s Local Electrode Atom Probe (LEAP) to examine experimental nanostructured FE-NI-MN-AL alloys developed at Thayer School. The University of Sydney is the only university in the world with a LEAP machine. According to Baker, who visited the Sydney facility last year, the students obtained composition profiles of the alloys by stripping off atoms one layer at a time. Dartmouth has filed a patent on the alloys.

Pushing for Alternative Fuels

Professor Lee Lynd, whose research centers on developing biological alternatives to fossil fuels, is trying to rally support from the American public. In “Growing Energy (PDF),” an article published by the Natural Resources Defense Council, co-author Lynd argues that an aggressive plan for developing cellulose-based biofuels could end America’s dependence on foreign oil by 2025. Lynd also has initiated talks with the National Corn Growers Association, pointing out that corn and other sources of cellulose used in biomass conversion could provide a major new revenue stream for farmers.

Ice Engineer Aids NASA

Professor Erland Schulson, director of Thayer School’s ice research lab, is helping NASA’s Space Shuttle Return-to-Flight Program analyze the ice that builds up on the shuttle’s super-cooled external fuel tank. Because debris from Space Shuttle Columbia’s external tank resulted in the loss of the orbiter, NASA wants to know how much ice can accumulate on the tank without becoming a debris hazard.

ICEBREAKER: Ph.D. candidate Andrew Fortt prepares to test ice strength with a multi-axial loading system in Professor Erland Schulson’s lab. Photograph by Douglas Fraser.

NASA is simulating the conditions typical of launch days to see how much ice and frost build up on the external tank. The agency sends the ice to Schulson for strength and structural analysis. Using a multi-axial loading system, Schulson measures the force required to crush the ice, then returns the samples to NASA for ballistic impact testing.

The NASA work has expanded Schulson’s research. “In our previous research we’d only ever tested poly-crystal ice samples,” he says. “For NASA, we’ve now tested a single crystal form of clear, hard ice and discovered that it is extraordinarily strong.”

Ph.D. candidate Andrew Fortt and engineering research associate Daniel Iliescu are assisting with the analysis.

For more photos, visit our Research and Innovations set on Flickr.

Solar Windtraps

Scientists are closer to understanding how high-energy particles from the sun — the solar wind — enter Earth’s magnetic field. Thayer School Research Associate Hiroshi Hasegawa and an international team of colleagues have for the first time observed giant space vortices that trap plasma and energy from the solar wind. The finding, published in the August 12 issue of Nature, may help explain how Earth’s magnetic field lets in the solar plasma when it should be acting as a barrier.

The newly discovered vortices, known as products of Kelvin-Helmholtz instabilities, resemble curled ocean waves. “These vortices were really huge structures, about six earth radii across,” says Hasegawa, who has been analyzing the data collected by four satellites dubbed the Cluster. “This is the first time rolled-up Kelvin-Helmholtz vortices have been detected unambiguously. Past observations, which were based on single-spacecraft measurements, could not tell with certainty whether the waves along the magnetopause — the edge of Earth’s magnetic field — were large rolled-up vortices or only small ripples that do not trap the solar wind.”

One reason space physicists and engineers want to understand how the solar wind gets through the magnetopause is because the solar wind causes geomagnetic storms that can disable satellites, disrupt radio and radar systems, and create electrical surges in power transmission lines and telephone wires.

Hasegawa’s research, funded by NASA, is part of the International Living with a Star collaborative program investigating how variations in the sun affect the environments of Earth and other planets.

Speeds of Light

Red laser pulses beamed through distilled water demonstrated the reality of light precursors. Photograph by Douglas Fraser.

Ninety years after the phenomenon was first predicted, Thayer researchers have observed an elusive property of light: in some media, a flash of light breaks into constituent frequencies that travel further and faster than the flash as a whole. Called precursors, these strong, fast constituents have defied detection since 1914. But when Professor Ulf Österberg and Research Associate Seung-Ho Choi beamed 100-femtosecond (10^-15) pulses of red laser light into a 70-cm.-long tube of distilled water, they observed a new pulse which attenuated an order of magnitude less than a conventional pulse.

Precursors result from two phenomena: 1) light traveling through any transparent medium splinters into component frequencies; and 2) water, like many transparent materials, transmits certain frequencies of light exceptionally well. Splinters of light traveling at favored frequencies propagate efficiently, while others fade. But as the light travels, the favored frequencies change — and so do the precursors, further complicating detection. “The precursor is like soap in the bathtub,” says Österberg. “It’s like it’s alive, it’s breathing, it’s moving along and changing the whole time.”

Precursors, if controllable, could be useful in medical imaging, underwater communications, radar, and other applications. Österberg and Choi’s discovery was reported in AAAS Science online and in Physical Review Letters.

Red Tide Alert

Professor Daniel Lynch’s ocean circulation models recently helped coastal communities in Casco Bay, Maine, gain their first-ever advance warning of red tide, the annual shellfish contamination caused by toxic algae. The early warning came from a National Oceanic and Atmospheric Administration-funded project that analyzes wind, currents, and other oceanographic data collected by sensors on ships, satellites, and buoys. When data about a patch of toxic algae observed in the Gulf of Maine was fed into Lynch’s computer model, the result was an accurate prediction of where and when the red tide would wash ashore. The forecast allowed Maine officials to close shellfish beds to public harvest before contamination began.

Lynch’s work in Thayer School’s Numerical Methods Lab involves three-dimensional coastal ocean circulation models, including a nonlinear prognostic model that allows the circulation field to evolve over time.

Microwaves for Vision

Professor Stuart Trembly is investigating a less invasive alternative to laser eye surgery: reshaping corneas with microwave thermokeratoplasty (MTK). Microwave energy, applied around the pupil outside the field of vision, causes collagen fibers in the cornea to shrink, flattening the optical surface in the center of the eye. The procedure is fast, requires no cutting, and uses less expensive equipment than laser surgery.

Trembly has advanced the state of MTK therapy with two patented devices. One is an improved applicator with embedded sensors to measure temperature or mechanical strain of the cornea during the procedure; the other is a feedback system that analyzes the signals to determine precisely when the myopia is corrected.

The project, which received support from Thayer School Overseer Ralph Crump ’66 and his wife, Marjorie, created opportunities for student input. Luke Dalton ’99, Th’01 worked on the cooling system for the MTK applicator; Michael Barton Th’04 studied anisotropic thermal conductivity of the cornea; and M.S. candidate April Mohns ’03, Th’04 is currently working on a finite element treatment-planning model.

Trembly is chief scientific officer of ThermalVision, Inc., which was incorporated in the fall of 2002 to bridge the gap from laboratory to market. “Human trials,” says Trembly, “are scheduled to begin in about 18 months.”

Treating Prostate Cancer

Thayer School and Dartmouth Medical School researchers are investigating a novel approach to using photodynamic therapy (PDT) to treat early-stage prostate cancer. Professor Brian Pogue, research associate Bin Chen, and adjunct Professor Jack Hoopes are testing their hypothesis that PDT is effective when used to consecutively target prostate cancer cells and the tumor’s vascular system. PDT involves fewer side effects than prostate surgery, which can cause impotence and incontinence.

PDT is a two-step process. The subject is injected with a photosensitizer, then the tumor is treated by laser light irradiation. By adjusting the interval between drug administration and light irradiation, PDT can be directed at either tumor cells or blood vessels.

Current PDT protocols typically use either a relatively long drug-light interval to target tumor cells or a short drug-light interval to cause vascular occlusion. The Thayer School team’s protocol applies the same long-interval cellular-targeting PDT but follows it immediately with short-interval vascular-targeting PDT. The researchers believe that targeting the tumor’s vascular system is crucial since a single vessel supplies oxygen and nutrients for thousands of tumor cells.

Ongoing studies are focused on assessment of the anti-tumor effect in prostate cancer and the abilty to spare normal surrounding tissues. The research is jointly funded by the Department of Defense and the National Institutes of Health.

Detecting Breast Cancer

A team of Dartmouth engineers and medical researchers headed by Professor Keith Paulsen has released preliminary findings on how various imaging technologies can be used to detect breast cancer. Reporting in the May issue of Radiology, the journal of the Radiological Society of North America, the interdisciplinary team from Thayer School, Dartmouth Medical School, Norris Cotton Cancer Center, and Dartmouth-Hitchcock Medical Center, described baseline data that identify an array of tissue properties that can differentiate healthy breasts from cancerous ones.

For example, electrical impedance spectral imaging, by measuring the impedance of cell membranes, can distinguish electrical characteristics that vary from healthy to cancerous tissue. Microwave imaging spectroscopy sends microwave energy, which is sensitive to water, through the breast, while near infrared spectral imaging sends infrared light, which is sensitive to blood. Both techniques can distinguish between healthy cells and cancerous cells, which tend to have more water and blood than regular tissue.

Phase 1 of the study concentrated on 23 healthy women. The second phase focuses on women who have had abnormal mammograms. “We’re just now getting into the really exciting part,” says Paulsen. “We’ve started to get some information on what the normal breast is like, and now we have some information on the abnormal tissue.”

The project is at least 10 years away from providing commercial versions of the tests. “There’s a lot of ways we can improve the instrumentation,” Paulsen says, “and we’re still trying to understand what these images mean. These are new types of images that no one has ever looked at before.” Ideally, the imaging techniques will be combined into a single medical procedure.

Paulsen, with Professor Paul Meaney and Larry Gilman Th’95, has edited Alternative Breast Imaging: Four Model-Based Approaches, to be published this November by Springer.

De-icing Planes and Bridges

Sweden's Uddevalla Bridge will be de-iced by Petrenko. Photo courtesy Alpin Technik und Ingenieurservice GmbH.

Professor Victor Petrenko’s thin-film, pulse electro-thermal de-icing (PETD) method for airplanes had its first in-flight testing this year. The Goodrich Corp., which holds the license for PETD aerospace applications, bonded a thin titanium-alloy skin onto the outboard wings of a twin-engine plane and tested it in an icing wind tunnel, then in flight behind an icing tanker (an aircraft with a tail-mounted icing spray boom), and finally on several cross-country flights under natural icing conditions.

“The test pilots were quite pleased with the system,” says Dave Sweet, director of research and development at Goodrich. “All the ice was removed instantly with very little runback ice generated.” Testing on a business jet is scheduled for this winter.

“The beauty of the method,” says Petrenko, “is that only a very thin layer of ice directly at the ice-material interface is heated.” A single pulse of electricity melts the interfacial ice, and any ice build-up slides right off. Regular pulsing keeps surfaces ice-free while maintaining low overall power consumption.

Another PETD test is taking place on Sweden’s four-year-old Uddevalla Bridge, which has to be closed each winter because ice falls from its towers and cables. In August Petrenko traveled to Sweden to meet with the Swedish Road Administration and several companies involved in the de-icing project. The process involves heating a stainless-steel foil coating on the bridge towers and cables with a second-long electrical pulse. Full-scale implementation of a PETD system for the bridge will begin next year.

For more photos, visit our Research and Innovations set on Flickr.