This is not a medical story per se, except that there is so much hope invested into all things nano- to deliver the cures of the future, that even a chemical news story becomes important not to overlook. Would you toss away and not pass along the news about the discovery of the mechanism of crystallization at the nano level? Of course you would not.
So here it is, from the press office at the Brookhaven National Laboratory:
Using what is thought to be the world’s smallest pipette, two researchers at the U.S. Department of Energy’s Brookhaven National Laboratory have shown that tiny droplets of liquid metal freeze much differently than their larger counterparts. This study, focused on droplets just a billionth of a trillionth of a liter in size, is published in Nature Materials.
“Our findings could advance the understanding of the freezing process, or ‘crystallization,’ in many areas of nature and technology,” said Eli Sutter, a scientist at Brookhaven’s Center for Functional Nanomaterials (CFN) and the lead author of the study. “The accepted theory of crystallization, developed in the first half of the previous century, predicts that without impurities, a small solid core generated at random in the interior of the droplet initiates the phase transformation. Our experiments on very small droplets challenge this theory.”
To study the freezing process at the ultra-small scale, Eli Sutter and fellow researcher Peter Sutter use what is thought to be the world’s smallest pipette, a device capable of producing liquid droplets of a gold and germanium alloy with a volume of only a few zeptoliters (a billionth of a trillionth of a liter). Operated inside an electron microscope, this zeptoliter pipette suspends the tiny droplets so their phase transformations can be studied with high magnification.
To achieve a liquid state, the metallic alloy must be kept at a temperature above 350 degrees Celsius. When the temperature is lowered to about 305 degrees Celsius, the researchers observe a striking phenomenon: The liquid droplets develop surface “facets,” which are straight, planar sections on the otherwise spherical-shaped structures. The facets continually form and decay in an “ethereal dance” of the droplet shape. This “dance” can last for hours, but quickly stops if the temperature is lowered any further. At this point, the droplet solidifies into a structure that is determined by the ending positions of the dancing surface facets.