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Manufacturing Bits: March 31

Whiskey webs; cryo-electron holography.

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Whiskey webs
The production and sale of counterfeit wine and spirits is becoming a big and nefarious business.

Using time-lapse microscopy, researchers have developed a way to detect counterfeit whiskey. To detect counterfeit whiskey, the University of Louisville and North Carolina State University have uncovered the mechanism behind what researchers call “whiskey webs.”

Whiskey webs are web-like patterns that form when drops of American whiskey dry up on a surface, according to researchers. In effect, drops of liquid evaporate on the surface. This in turn forms a distinct pattern. The pattern depends on the type of liquid and the environmental conditions.

The patterns are distinctive for different whisky brands. The distinctive patterns could one day be used to identify counterfeit whiskeys, according to researchers.

To help determine the authenticity of a whiskey, researchers used time-lapse microscopy. As it turns out, researchers found drops of diluted American whiskeys–– but not the Scotch or Canadian versions–formed webbed patterns when dried on a glass surface.

Nonetheless, researchers examine droplets of diluted American whiskey. The non-volatile organic compounds tend to cluster together. They were also driven to the surface of the droplet.

“As the surface area of the droplet decreased, the monolayers collapsed, creating strands of the web,” according to researchers in ACS Nano. “The researchers showed that different American whiskeys showed unique web patterns that could be correctly matched to unknown samples more than 90% of the time. The distinctive webs arise from the unique combination of solutes in each whiskey.”

Cryo-electron holography
The Okinawa Institute of Science and Technology Graduate University (OIST) has developed a new and less expensive version of a cryogenic electron microscope (cryo-EM).

The new technology from OIST is called cryo-electron holography. Using this technique, researchers have created images of three different biomolecules.

Cyro-EM is often used in structural biology and other applications. In one application, a cryo-EM is used to freeze biomolecules mid-movement. Then, the structure is imaged at atomic resolutions. The system allows researchers to produce films that reveal how molecules interact with each other.

In operation, a cryo-EM fires electrons at a sample. The electrons interact with atoms in the sample. The electrons scatter and hit a detector in the system, which in turn enables an image of the sample.

A problem occurs when the system is used at high energies. A small number of scattering events occur. The electrons interact very weakly with the atoms in the sample.

To overcome these challenges, researchers added a new imaging function to a scanning-electron microscope. Now, the system can switch to a different imaging technique called cryo-electron holography. “In holographic mode, an electron gun fires a beam of low-energy electrons towards the specimen so that part of the electron beam passes through the ice and specimen, forming an object wave, while the other part of the electron beam only passes through the ice, forming a reference wave,” according to OIST. “The two parts of the electron beam then interact with each other, like colliding ripples in a pond, creating a distinct pattern of interference–the hologram.”

As a result, the detector in the system can distinguish scattering by the specimen from scattering by the ice film. Researchers can compare the two parts of the beam to gain information.

“Electron holography provides us with two different kinds of information – amplitude and phase – whereas conventional cryo-electron microscopy techniques can only detect phase,” said Hidehito Adaniya, a researcher at OIST. “Building this microscope was a long and challenging process. As well as being cheaper and simpler to use, our microscope utilizes low-energy electrons, which could potentially improve the contrast of the images.”



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