Manufacturing Bits: May 22

Exotic water; tracking water molecules; cryo-electron microscopy.


Exotic water
The Deutsches Elektronen-Synchrotron (DESY) organization, Uppsala University and SLAC have turned a large X-ray laser into the world’s fastest water heater.

Using an X-ray free-electron laser from the SLAC National Accelerator Laboratory, researchers have heated water from room temperature to 100,000 degrees Celsius in less than a tenth of a picosecond or a millionth of a millionth of a second. The experiment produces what researchers call exotic states of water. The idea is to learn more about the various states of water, which could be used for probing biological and other samples with X-ray lasers.

In the experiment, researchers used SLAC’s Linac Coherent Light Source (LCLS). Then, they shot intense and ultrashort flashes of X-ray free-electron lasers at a jet of water. After being hit with an X-ray pulse up to 25 femtoseconds, the water showed little or no signs of changing.

But in less than 75 femtoseconds, or 75 millionths of a billionth of a second (0.000000000000075 seconds), the water goes through a phase transition under which it goes from a liquid to a plasma. A plasma is a state of matter. In plasma, the electrons have been removed from the atoms. This, in turn, causes an electrically charged gas.

An illustration shows water molecules flying apart after some of their electrons are punched out by an X-ray laser pulse. The process heats the water to 100,000 degrees Celsius within 75 millionths of a billionth of a second. Oxygen atoms are in red and hydrogen atoms in white. (Carl Caleman, DESY/Uppsala University)

“It is not the usual way to boil your water,” said Carl Caleman of the Center for Free-Electron Science (CFEL) at DESY and Uppsala University. “Normally, when you heat water, the molecules will just be shaken stronger and stronger.

“(In this experiment), our heating is fundamentally different,” Caleman said. “The energetic X-rays punch electrons out of the water molecules, thereby destroying the balance of electric charges. So, suddenly the atoms feel a strong repulsive force and start to move violently.”

Olof Jönsson from Uppsala University said: “But while the water transforms from liquid to plasma, it still remains at the density of liquid water, as the atoms didn’t have time to move significantly yet. It has similar characteristics as some plasmas in the sun and in the gas giant Jupiter, but has a lower density. Meanwhile, it is hotter than Earth’s core.”

Tracking water molecules
DESY, SLAC, Stockholm University and others have tracked the movements of molecules in liquid water that occur in less than 100 millionths of a billionth of a second or femtoseconds

In the experiment, researchers took photographs of water molecules using ultrafast X-ray photon correlation spectroscopy. This technology bounces X-ray pulses off molecules. This in turn produces diffraction patterns.

Researchers also varied the duration of the X-ray pulses. This, in turn, could cause a blur of the resulting picture. Using that data, researchers have been able to extract information about the motion of the molecules. “The key to understanding water on a molecular level is watching the changes of the hydrogen-bond network, which can play a major role in biological activity and life as we know it,” said Anders Nilsson, a professor at Stockholm University.

Added Stockholm University researcher Fivos Perakis: “It is a brand-new capability to be able to use X-ray lasers to see the motion of molecules in real time. This can open up a whole new field of investigations on these timescales, combined with the unique structural sensitivity of X-rays.”

An illustration shows the “blurring” effect caused by water molecules moving during imaging with the X-ray laser. (Fivos Perakis/Stockholm University)

Cryo-electron microscopy
The National Institutes of Health (NIH) is supporting efforts to broaden biomedical scientists’ access to cryo-electron microscopy (cryo-EM).

The Transformative High Resolution Cryo-Electron Microscopy program is creating three national cryo-EM service centers to provide access to the technology and is supporting the development of cryo-EM training curricula to build a skilled workforce. The awards are anticipated to total $129.5 million, pending the availability of funds, and the centers are expected to offer limited services by late 2018 as they build to full capacity.

Cryo-EM is a method used to image frozen biological molecules without the use of structure-altering dyes or fixatives or the need for crystallization to provide a more accurate model of the molecules and a greater understanding of biological function.

The three national centers will be established with six-year awards at the New York Structural Biology Center, New York City; the Oregon Health & Science University, Portland, in partnership with the Pacific Northwest National Laboratory, Richland, Washington; and the SLAC National Accelerator Laboratory at Stanford University, Menlo Park, California.

The centers will provide scientists with access to state-of-the-art cryo-EM technology and training, from sample preparation to collection of high-resolution data and computational analysis.

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