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2018 Spotlights

Microbes affect everything from the human body to the decomposition of plant and animal waste in the environment. The health and habits of these organisms can have a huge impact on every facet of life. Steven Wilhelm, professor of microbiology, believes viruses hold similar importance. 

“The world as we know it now is really a microbial planet. Microbes are the interface of our daily lives and how the world works,” he said. “They recycle nutrients, they play important roles in carbon fixation and photosynthesis—and these microbes are all susceptible to viruses.”

Viruses are incredibly abundant: hundreds of thousands of them can exist in a puddle. According to Wilhelm, they’re also quite fragile, meaning they must reproduce quickly to maintain such a large population. 

To study these viruses further, Wilhelm and his team have partnered with Dale Pelletier, senior staff scientist in the Biosciences Division at ORNL. Pelletier is studying the microbial community within sphagnum, or peat bogs. Sphagnum is responsible for approximately 20 percent of the carbon storage on the planet. 

Wilhelm and student Helena Pound“It acts as such a good carbon sink because the sphagnum plants themselves change the chemistry of the system so that typical microbes do not grow very well. As a result they don’t break down the carbon, so as the sphagnum dies the carbon builds up,” said Wilhelm.

His team is investigating what could be controlling the existing microbes in the peat bogs other than chemistry. He believes the answer is viruses.

Doctoral student Helena Pound is currently working with bioinformatics to determine how prevalent these viruses are. Her work will include snapshots as well as work over time, which should provide a better picture of how the viruses operate.

“I believe in 10 to 15 years, we will realize viruses are just as important as microbes,” said Wilhelm. “When we then build models of how these microbial systems work, we’ll have to start to account for the viral community.”

Human history is divided into time periods based largely around the types of tools or technology being employed. The Iron Age was characterized by the increased use of iron weapons and tools, edging out the previously used bronze. This iron, however, wasn’t simply iron. It was iron heated with carbon, marking the start of a new era when humans realized that metal alloys could perform better than single metals. 

Alloys are the result of mixing two or more metallic elements together with the goal of creating more desirable attributes such as rust or heat resistance. The search for better alloys continues into the present, as scientists chase super alloys for use in a variety of technologies. Seungha Shin, assistant professor of mechanical, aerospace, and biomedical engineering, is on the hunt for one such alloy. 

“We are studying superalloys, which can have high stress and heat resistance,” he said. “To achieve high-efficiency vehicles or airplanes, we need some lightweight materials. Normally light metals are not that good at high temperatures, so we need to develop some new materials.”

If sufficiently heat- and stress-resistant materials can be developed and used to build engines, vehicles can become more fuel efficient simply by virtue of being lighter. Shin’s team is working to create such an alloy with aluminum, focusing their work on its thermal transport properties.

Shin’s LDRD partner Amit Shyam, research scientist at ORNL, is also studying the effects of microstructures on alloy properties. Shin’s team contributes a much-needed level of expertise in thermal transport properties to their shared goal. Shin hopes to conclude the project with a deeper working relationship with his ORNL partner and enough useful data to secure more funding from external sources.

Salt is a complicated molecule. It can make bland food more palatable and even melt hazardous ice on roads. However, the same salt that makes roads safer for driving, if not removed promptly, can cause major issues for the vehicles that drive through it. Over time, brine kicked up from the road onto the car can corrode and rust the metal parts, ruining engines and destroying paint jobs.

The same can be said for the metals within molten salt reactors and concentrating solar power plants. Molten salt reactors are a type of nuclear reactor using salts as either a coolant or fuel, and concentrating solar power plants use liquid salts as a heat transfer and storage medium. A major area of research involves the effectiveness of different materials within the reactors, especially those coming into contact with salts.

Student working in Rawn's labClaudia Rawn, associate professor of materials science and director of the Center for Materials Processing, and her JDRD team are investigating the effects of these salts on chromium-containing alloys in conjunction with Stephen Raiman, research associate in corrosion science at ORNL.

“Our colleagues at Oak Ridge are studying the chromium in structural materials that are in contact with molten salts in places including concentrated solar or nuclear reactors,” said Rawn. “The molten salt is in contact with different structural components and there is concern about the chromium leaching out into the salt.”

Rawn’s team plans to complement the work at ORNL by using X-ray diffraction to study the effects of these salts on structural materials that contain chromium. Raiman’s team will be investigating the interactions between molten salts and chromium in structural alloys, while Rawn will look at the salt itself.

In order to take an atomic look at the salts, Rawn’s team will use the recently established diffraction facility at the UT-ORNL Joint Institute for Advanced Materials. She hopes their work will provide an important piece of the molten salt–chromium interaction puzzle and serve as a stepping stone to future collaborations.

Rush-hour traffic is part of life in most metropolitan areas in the US. The presence of large numbers of people traveling in the same general direction at the same time is bound to result in congestion and frustration. Picture that same rush hour during the summer. Air conditioners crank as heat ripples off the blacktop and, inevitably, somewhere along the way a car is pulled to the side of the road, steam pouring from under the hood.

Overheating is an issue for much of the technology that defines modern life. Cars, computers, mobile phones—all are subject to the effects of too much heat. As technology continues to speed up and devices get smaller, this heat problem compounds as internal parts shrink and move closer together. Jian Liu, assistant professor of physics and astronomy, is working to address this issue with his JDRD project.

It all starts with an electron. Transistors, the building block of modern electronics and technology, work by moving an electron back and forth across an interface. This switching action can be sped up by decreasing the distance the electron has to travel through the interface, letting the device operate faster. This is where heat can become a problem.

“When the electron travels, it generates heat because it interacts with other atoms. The electron is trying to go and at some point it’s going to hit an atom, causing the atom to vibrate,” said Liu. “Basically, you’re transferring the energy from the electron to the atom and that’s how it generates heat.”

Because heat has the ability to affect device performance, its management is an important factor in technology development. Liu’s team hopes to find a way to predict how heat is moved within a device, laying the groundwork for more effectively controlling how and where heat is transported out of the device.

“If you can control heat transport, you can have an electronic device that works faster. Then you can maybe pack your devices into a more confined area and make sure there’s no hot spot,” said Liu.

His JDRD team is working to build a prototype that will use the same interface for both electron and heat movement. Once complete, the prototype will be given to Lucas Lindsay, materials research scientist at ORNL, for experimental testing and comparison with computational predictions. The teams hope to have generated preliminary data by the end of the funding year.

Since the earliest days of farming, ensuring adequate food production to consistently feed a population has been the primary goal. This goal has not changed in the thousands of years since plant cultivation began, al though the mechanisms of achieving it have evolved considerably. Irrigation, pesticides, automated machinery—all these advancements have arisen from the need to produce enough food to keep pace with the growing numbers of humans on the planet.

In recent years, this drive has shifted toward the plants themselves. Genetically modified seeds designed to withstand drought and blight have become commonplace. Sarah Lebeis, assistant professor of microbiology, believes the next advances will be made by studying plant microbiomes, specifically the effects of certain bacteria on those microbiomes. 

“One thing we’ve found is that the more we look at which microbes associate with plants, we find these bacteria over and over again. They can be pathogens or they can promote growth of the plants,” she said. 

Some agricultural companies have seized on the idea that plants can be helped with the introduction of so-called good microbes and have begun marketing products designed to do just that. Lebeis describes these products as plant probiotics and emphasizes that they are not always effective.

Sarah Lebeis“It’s really exciting that people are trying to find these ultimate microbes that can change the way plants grow, but they’re not always going to work. When they don’t work, we want to know why they don’t work,” she said.

She believes Streptomyces, a particularly large genus of bacteria, is playing a role in determining which microbes are allowed into a plant. Lebeis suggests that, in addition to keeping out harmful microbes, the Streptomyces may also be preventing some beneficial microbes from entering the plant’s system.

Lebeis’s ORNL collaborator, Daniel Jacobson, chief scientist for computational systems biology, has provided her team with a large data set to serve as the basis of her JDRD work. By the end of the year she hopes to have compiled a list of microbes that either work with or are repelled by Streptomyces

“We want to see who they influence, who they let in and who they don’t. The JDRD will help us generate a giant list of hypotheses, which we’re so excited about,” said Lebeis.