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The Laboratory
in the News

New method looks at protein folding
A new experimental method allows scientists to investigate the behavior of proteins under nonequilibrium conditions one molecule at a time. Developed by an international team of researchers, including Lawrence postdoctoral fellow Olgica Bakajin, this method will help researchers understand the fundamental biological process of protein folding. The work marks the first time protein-folding kinetics has been monitored on the single-molecule level.
Proteins are long chains of amino acids that loop about each other. Although a protein folds in various ways, only one form allows it to function properly. A misfolded protein can do serious damage and is a factor in diseases such as Alzheimer’s and cystic fibrosis as well as in many cancers.
The research team, which included scientists from the National Institutes of Health and the Physikalische Biochemie Universität Potsdam in Germany, developed a microfluidic mixer to examine the protein-folding reaction. The mixer allowed them to examine a protein on a single-molecule level at defined times after the reaction began.
“With this method,” says Bakajin, “we are able to isolate intermediate states that under equilibrium conditions exist only for a brief period of time.” As a result, the team obtained data about the protein-folding reaction that were never available from ensemble measurements or even from the newer, single-molecule equilibrium measurements.
“With this method,” says Bakajin, “we are able to isolate intermediate states that under equilibrium conditions exist only for a brief period of time.” As a result, the team obtained data about the protein-folding reaction that were never available from ensemble measurements or even from the newer, single-molecule equilibrium measurements.
Results from this study were published in the August 29, 2003, issue of Science.
Contact: Olgica Bakajin (925) 422-0931 (bakajin1@llnl.gov).

Mapping the phonons in plutonium
In collaboration with the European Synchrotron Radiation Facility in Grenoble, France, and the University of Illinois at Champaign–Urbana, Livermore scientists have, for the first time, fully mapped the phonons in gallium-stabilized delta plutonium. The landmark experiment, which was led by Livermore chemist Joe Wong, promises to reveal much about the physics and material properties of plutonium and its alloys.
To measure the phonon dispersions, the research team used a high-resolution inelastic x-ray scattering technique developed at the European Synchrotron Radiation Facility. A microbeam from the highly brilliant x-ray synchrotron source impinged on a single grain in a polycrystalline alloy of delta plutonium and gallium.
Phonon dispersion data are fundamental to understanding the properties of plutonium materials, such as force constants, sound velocities, elasticity, phase stability, and thermodynamics. But experimental observations of plutonium are extremely difficult because of the technical and safety issues involved in such studies. Until now, scientists couldn’t measure phonon dispersions because they couldn’t grow the large single crystals needed for inelastic neutron scattering.
“The new phonon data will greatly enhance scientists’ understanding of the transformations and phases plutonium undergoes in different environments and over time,” says Wong. “Basic knowledge of this sort is much needed and contributes greatly to the Laboratory’s stockpile stewardship mission.”
Results from this research appeared in the August 22, 2003, issue of Science.
Contact: Joe Wong (925) 423-6385 (wong10@llnl.gov).

Seismologists study mining blasts in the Baltics
In the northern region of Norway lies a seismic monitor sensitive enough to detect mining blasts as small as a few tons of explosive in neighboring Russia and Sweden. The seismic station, named ARCES, is one of at least a dozen temporary stations that were originally set up to ensure that countries were adhering to the Comprehensive Test Ban Treaty of 1996. It is now being used by Laboratory scientists to screen commercial mining explosions. The overall goal of the program is to distinguish whether a seismic signal is due to an earthquake, a conventional explosion, or a nuclear event.
The three-year project is providing real-time data on explosions conducted at principal mines within 500 kilometers of the ARCES seismic station. The Laboratory is partnering with NORSAR—a nonprofit Norwegian research organization—and the Kola Regional Seismological Center in Russia to characterize the range of mining going on in northwest Russia and Sweden. From the signals observed by seismic stations, these researchers hope to determine whether the observed events are mine blasts and whether these blasts occur aboveground or underground.
Some minor natural seismicity in the area is caused by a rebound of Earth’s crust following the melting of the continental ice sheet at the end of the Ice Age. However, according to David Harris, the Laboratory’s principal investigator on the project, the majority of observed events are explosions at the many mines in the area. The diverse types of mining explosions make the area a natural laboratory for studying commercial explosions.
“The purpose is to observe how variable mining explosions are compared to nuclear explosions or earthquakes,” Harris says. “The greater the variability, the more difficult it will be to devise effective screens for normal blasting activity.”
To date, the project has collected data on 1,118 explosions in the Kola Peninsula and waveform data for about 700 of those events.
Contact: David Harris (925) 423-0617 (harris2@llnl.gov).

First Jasper gas-gun shot on target
On July 8, 2003, the Laboratory achieved a major milestone with the firing of the JASPER gas gun at the Nevada Test Site. “The JASPER team successfully executed our first plutonium shot today at 2:35 p.m.,” said Mark Martinez, test director. “The data demonstrate superb quality, and a preliminary analysis indicates that JASPER will meet its intended goal of generating high-precision plutonium data.”
Livermore scientists fired a tantalum projectile at more than 5 kilometers per second at a plutonium target. The impact produced a high-pressure shock wave that passed through the target in a fraction of a microsecond. During this extremely brief period, diagnostic equipment measured the properties of the shocked plutonium inside the target. These shock physics experiments complement the ongoing subcritical experiments at the Nevada Test Site.
JASPER, an acronym for Joint Actinide Shock Physics Experimental Research, is a 20-meter-long, two-stage gas gun. It was built and activated at a total cost of $20 million inside existing facilities within Area 27 at the Nevada Test Site.
Inside the gun’s first stage, hot gases from a burning propellant drive a heavy piston down a pump tube, compressing a gas. That gas—typically hydrogen—builds up to extremely high pressures, breaks a valve, and enters the narrower barrel of the second stage, propelling the projectile housed in the barrel toward the target. JASPER can fire small projectiles at velocities of up to 8 kilometers per second, which is more than 24 times the speed of sound.
The gas gun completed a series of 20 inert or nonnuclear shots to qualify it for use with nuclear materials. This first plutonium shot marks the culmination of years of effort in facility construction, gun installation, system integration, design reviews, and authorizations to bring the experimental facility on line. The gun can fire about 24 experiments per year.
Following this landmark experiment, Linton Brooks, administrator for the National Nuclear Security Administration, concluded, “Our national laboratories now have at their disposal a valuable asset that enhances our due diligence to certify the nuclear weapons stockpile in the absence of underground nuclear weapons testing.”
Contact: Neil Holmes (925) 422-7213 (holmes4@llnl.gov).

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UCRL-52000-03-11 | November 7, 2003