Dr. Lindsay SextonDr. Lindsay Sexton, Senior Scientist, Nonproliferation Policy Support, Savannah River National Laboratory

When Senior Scientist Lindsay Sexton of DOE's Savannah River National Laboratory first left for college, the plan was to study medicine. But after a few biology classes, the pre-med student realized she needed a new calling. Then her chemistry professor had one simple request — she was asked to help with research investigating the effects of metal overlayers on self-assembled monolayers. It was at that time that Sexton realized she had a future in research and development.

“I really liked the problem solving aspect of research and the freedom to explore new ideas in the laboratory,” said Sexton, who works in Nonproliferation Policy Support at SRNL. “The professor I worked for encouraged me to go to graduate school for chemistry and pursue a PhD. I ended up at the University of Florida where I worked on the development of protein sensors using single nanopore membranes.”

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Typical gold shop hood used to purify gold by superheating the gold/mercury amalgam until the mercury vaporizes. The vaporized mercury is directed outside the shop into the open air where it descends onto homes, water and food of the local populations. Image credit: Habegger et. al.Argonne/EPA system captures mercury from air in gold shops

In any given year, workers in artisanal and small-scale gold mining shops in remote locales like Brazil and Peru release an estimated 700 tons of airborne mercury from their rooftops.

Collectively, these shops purify nearly 20 percent of the world’s gold supply before it is shaped and sold in stores. Through a generations-old process, small-scale miners use hand tools and chemicals to extract gold from the ground. Miners use mercury as an easy way to extract gold pieces during the sifting process, which separates out dirt and other materials. The resulting gold and mercury mixture is then brought to shops that separate this harmful chemical from the gold.

Gold is separated out by burning off mercury with high-temperature torches that release vaporized mercury into the air. Eventually, these vapors fall back to the ground and contaminate food and water.

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DOE Pulse
  • Number 431  |
  • January 26, 2015
  • ‘Iron Sun’ is not a rock band, but a key to how stars transmit energy

    Physicist Jim Bailey of Sandia National Laboratories observes a wire array that will heat foam to roughly 4 million degrees until it emits a burst of X-rays that heats a foil target to the interior conditions of the sun. (Photo by Randy Montoya) Working at temperatures matching the interior of the sun, researchers at the Z machine at DOE's Sandia National Laboratories have been able to determine experimentally, for the first time in history, iron’s role in inhibiting energy transmission from the center of the sun to near the edge of its radiative band — the section of the solar interior between the sun’s core and outer convection zone.

    Because that role is much greater than formerly surmised, the new, experimentally derived amount of iron’s opacity — essentially, its capacity for hindering the transport of radiative energy originating in nuclear fusion reactions deep in the sun’s interior — helps close a theoretical gap in the Standard Solar Model, widely used by astrophysicists as a foundation to model the behavior of stars.

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  • Ames scientists use genetic markers to discover the rhizosphere

    Marit Nilsen-Hamilton, an Ames Laboratory scientist and professor in the Roy J Carver Department of Biochemistry, Biophysics and Molecular Biology at Iowa State University, works with her research team to develop methods ofnon-destructive imaging of biological systems. From left: lab manager and technician Lee Bendickson; graduate research assistant Ivan Geraskin; Marit Nilsen-Hamilton (front), Ames Laboratory scientist George Kraus (back); and graduate research assistant Judhajeet Ray (foreground). It’s a science lesson so fundamental that we teach it to small children, planting bean seeds in Styrofoam cups: plants take nutrients from the soil to grow.

    It is surprising, then, that the complex interchange between the microorganisms in soils and the cellular activities of plants’ root systems, what scientists call the rhizosphere, remains one of science’s great mysteries.

    “We want to know how plants and microbes in the soil talk to each other,” said Marit Nilsen-Hamilton, an Ames Laboratory scientist and professor in the Roy J Carver Department of Biochemistry, Biophysics and Molecular Biology at Iowa State University. “We know they’re communicating with each other, but how? Multicellular communities are vastly more complex than we currently understand. How do we go about finding out?”

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  • Model explores location of future U.S. population growth

    This 3-D visualization represents projected changes in U.S. population between 2010 and 2050 as predicted by a new Oak Ridge National Laboratory model. Areas seen in red indicate higher levels of population growth, whereas the vertical spikes signify population growth with new land development. Researchers at DOE’s Oak Ridge National Laboratory have developed a population distribution model that provides unprecedented county-level predictions of where people will live in the U.S. in the coming decades.

    Initially developed to assist in the siting of new energy infrastructure, the team’s model has a broad range of implications from urban planning to climate change adaptation. The study is published in the journal Proceedings of the National Academy of Sciences.

    “We do a census every 10 years because those data help us do long-term socioeconomic planning,” said Budhendra Bhaduri, who leads ORNL’s Geographic Information Science and Technology group. “Population projection numbers are important, but many pressing societal needs also require an understanding of where people are going to be. This has always been a challenge; we’ve never had a good method to make future projections spatially explicit.”

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  • On the right track for tropical clouds

    Large-scale vertical lifting and the decline of mid-level drying are vital to initiating and propagating MJO deep convection. Photo courtesy of Adam H. Sobel, The Madden-Julian Conversation. Think of a tropical storm about the size of Alaska. Large and lumbering, the Madden-Julian Oscillation (MJO) affects weather patterns in every corner of the world. Unlike its well-known cousin El Niño, the MJO is both variable and unpredictable, earning the title of the largest and least understood element in the tropical atmosphere. However, scientists at DOE's Pacific Northwest National Laboratory and collaborators at the Indian Institute of Technology recently discovered what forces cause the MJO to begin and keep moving. Understanding the MJO could allow accurate weather forecasts beyond 10 days, enabling better prediction of severe storms.

    The team began with data collected during the ARM MJO Investigation Experiment (AMIE)/Dynamics of the Madden-Julian Oscillation (DYNAMO) field campaigns. The campaigns took place in the winter of 2011 over the Indian Ocean. With this data, they ran high-resolution regional model simulations.

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