NEWS OF THE WEEK
IMAGING NANOPARTICLES IN LIQUIDS MATERIALS: Microscopy method captures near-atomic 3-D structure
still long enough to have their pictures taken. Neither do nanoparticles floating and rotating around in solution. But that hasn’t stopped a team of researchers from producing three-dimensional images of angstrom-sized metal particles in solution at near-atomic resolution (Science 2015, DOI: 10.1126/science.aab1343). The imaging technique used by the researchers, based on transmission electron microscopy (TEM), may enable scientists to monitor dynamics of individual particles within a colloid in their native state. Structural details gleaned from the imaging method may also lead to new uses for nanoparticles in catalysis, biological imaging, and other areas. TEM generates 2-D projections of 3-D objects. One way microscopists produce 3-D TEM images is by painstakingly piecing together multiple 2-D images of a rigidly supported sample as it is tilted at various angles. Another way is to record images of many identical particles trapped in various orientations in ice. But those methods aren’t suitable for high-resolution imaging of nanoparticles that are freely rotating in solution. So A. Paul Alivisatos and Alex Zettl of the University of California, Berkeley; Jungwon Park and David A. Weitz of Harvard University; and coworkers devised a way to sidestep that limitation. Drawing on a liquid-sampling technique the re-
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IDGETY KIDS AND SKITTISH BIRDS don’t sit
searchers reported in 2012 , they packaged a few droplets of colloidal platinum nanoparticles in a nanosized graphene bubble. Then they used a microscope equipped with a highly sensitive detector to zoom in on individual particles and record many short-exposure images. Because the particles were constantly moving, the images were inherently low quality. But by applying a computational technique the researchers developed for this purpose, they were able to produce high-resolution 3-D reconstructions of randomly moving nonidentical particles. This work is likely to make an impact in biological imaging, catalysis, and other fields, says Joerg R. Jinschek, a TEM specialist for microscope maker FEI who is based in the Netherlands. Jinschek explains that attaching a colloidal particle to a rigid surface—as has been done for imaging purposes in the past—can alter its structure. Because structure and other properties often depend on a particle’s state or environment, researchers want detailed information about nanoparticles in their natural states, Jinschek says. He adds that being able to image freely moving nanoparticles in liquids, as was done in the new study, will help scientists determine relationships between a nanoparticle’s structure and its function.—MITCH JACOBY
FREE-FLOATING The riblike structures seen here depict atomic planes in two nonidentical platinum particles (2 nm in diameter), which were imaged while they drifted and rotated freely in solution.
RENEWABLE FUELS LanzaTech’s waste-gas-to-ethanol process arrives in Europe Ethanol is usually made from crops such as corn or wheat. But Skokie, Ill.-based LanzaTech has developed a process to obtain the fuel from waste gas, such as the carbon monoxide produced by steel plants. Steelmakers in Asia were the first to try the technology, and now it’s coming to Europe. ArcelorMittal, which calls itself the world’s leading steel and mining company, says it will build a $100 million facility at a steel mill in Ghent, Belgium, that will produce 15 million gal of ethanol per year using LanzaTech microbes that convert CO into the alcohol. If the plant works, ArcelorMittal plans to add
ethanol production across its European operations. Gaining a foothold in Europe will surely add to the buzz around LanzaTech. Last week, the company received a 2015 Presidential Green Chemistry Challenge Award (see page 5). LanzaTech has had success in Asia, including collaboration with China Steel, but its fermentation technology isn’t well-known. Industry watchers expect to learn more as it is implemented in Europe. “It means further validation and is another full step toward mainstream understanding and acceptance,” says Sam
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Nejame, chief executive officer of the technology consultancy Promotum. Making ethanol from emissions could be profitable in Europe, Nejame adds, thanks to significant carbon credits awarded to such fuel. Replacing gasoline with LanzaTech ethanol reduces carbon emissions by 80%, the company says. According to ArcelorMittal, roughly half of the carbon used to make steel becomes CO waste. Plants can either flare the gas or combust it for heat, releasing CO2 either way. Making ethanol will have a meaningful impact on ArcelorMittal’s carbon footprint, the company says.— MELODY BOMGARDNER
