Lab Report

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The Lab Report is a weekly compendium of media reports on science and technology achievements at Lawrence Livermore National Laboratory. Though the Laboratory reviews items for overall accuracy, the reporting organizations are responsible for the content in the links below.

Jan. 19, 2018

mice
New LLNL research dubbed “brain-on-a-chip” could eliminate the need for animal testing.

No more lab rats?

Researchers at Lawrence Livermore have devised a new use for “brain-on-a-chip” technology: testing the effects of biological and chemical agents on the brain over time. This work is part of an ever-growing body of research dedicated to developing “brain-on-a-chip” technology in hopes that, one day, it may eliminate the need for animal testing.

The brain-on-a-chip is a wafer of semiconductors that researchers affix a network of nanowires. When brain cells are introduced onto the chip, they can use the nanowire as scaffolding to build functional neuronal circuits that mimic the interconnectivity of neurons in the brain. Once the lattice is constructed, researchers cannot only observe the connectivity as-is but study the impact of disease and trauma.

elephants
Once numbered at more than a million, the population of African elephants fell 30 percent between 2007 and 2014, to about 350,000, mainly due to poaching for ivory

The elephant in the room

Scientists are using information gleaned from both illegal ivory art and elephant dung to provide clues that could help save the lives of pachyderms that are being slaughtered for their tusks in Africa.

The work involves cutting up seized artifacts and subjecting them to carbon dating to determine when the elephants were killed and whether it was before or after the international ban of ivory sales in 1989. DNA from the ivory art is then compared to a DNA database derived from elephant dung to pinpoint where they lived.

The data will tell the story of where and when an elephant died. The DNA and radioisotope analysis also can help prosecute traffickers. In a 2013 study, Lawrence Livermore scientists helped convict an ivory trafficking kingpin in Togo by providing evidence that his ivory came from Cameroon and Gabon, two of the hardest hit countries in the elephant slaughter. Radioisotope analysis by LLNL showed the ivory came from elephants killed as recently as 2010, not before the 1989 ban as the trafficker claimed.

nanotube
High water flow going through a narrow carbon nanotube that looks like a water pipe.

Seeing clean water through the salt

Lawrence Livermore researchers have shown that efficient water transport in carbon nanotubes with openings of less than one nanometer (a human hair is 100,000 nanometers wide) can be used to desalinate water.

In these human-made straws, the water transport was fast, surpassing that in a biological “gold standard” protein. The faster transport was due to extreme water confinement in carbon tubes that also did not interact with the water, letting it flow more freely. Still, the tubes could maintain high ion selectivity even in seawater-like conditions.

Narrow carbon nanotubes could make drinking water from saltwater. The tubes squeeze water into a single file chain. Further, the tubes controllably filter the salt ions. The work establishes carbon nanotubes for energy-efficient water purification. It also introduces the structures for industrial separations and advanced circuits for developing computer technologies.

woodpile
LLNL researchers can print woodpile lattices with submicron features a fraction of the width of a human hair. Image by Jacob Long and Adam Connell/LLNL

Itty bitty 3D printing

Lawrence Livermore researchers have improved the capabilities of two-photon lithography (TPL), a high-resolution 3D printing technique capable of producing nanoscale features smaller than one-hundredth the width of a human hair.

TPL typically requires a thin glass slide, a lens, and an immersion oil to help the laser light focus to a fine point to carry out curing and printing photoresistive materials. It can produce features smaller than the laser light spot (less than 150 nm), a scale no other printing process can match.

The new technique bypasses the usual diffraction limit of the other methods, as the photoresist material that cures and hardens to create structures (previously a trade secret) simultaneously absorbs two photons instead of one.

mars
New LLNL research shows that trapped gasses in ancient Martian meteorites pin down the timing and effectiveness of atmospheric escape processes that have shaped Mars’ climate.

Mars has been bone dry for billions of years

Liquid water is not stable on Mars’ surface because the planet’s atmosphere is too thin and temperatures are too cold. However, at one time, Mars hosted a warm and wet surface environment that may have been conducive to life.

New research by Lawrence Livermore cosmochemist Bill Cassata shows that, by looking at trapped gasses in ancient Martian meteorites, the timing and effectiveness of atmospheric escape processes that shaped Mars’ climate can be pinned down.

Cassata analyzed the Martian atmospheric gas xenon (Xe, in two ancient Martian meteorites. The data indicate that early in Martian history there was a sufficient concentration of atmospheric hydrogen to mass fractionated Xe (selectively removed light isotopes) through a process known as hydrodynamic escape. However, the measurements suggest this process culminated within a few hundred million years of planetary formation (more than 4 billion years ago), and little change to the atmospheric Xe isotopic composition has occurred since this time.

This differs significantly from Earth, where Xe isotopic fractionation was a gradual process that occurred throughout much of planetary history, indicating that atmospheric dynamics on the two planets diverged early in the history of the solar system.