Category Archives: Physics

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Insects in Freezing Regions Have a Protein that Acts Like Antifreeze

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From the Journal: Journal of Chemical Physics

WASHINGTON, D.C., April 2, 2019 — The power to align water molecules is usually held by ice, which affects nearby water and encourages it to join the ice layer — to freeze too. But in the case of organisms living in freezing habitats a particularly powerful antifreeze protein is able to overpower the grip ice has on water and convince water molecules to behave in ways that benefit the protein instead.

In the latest study this week in The Journal of Chemical Physics, from AIP Publishing, scientists are taking a closer look at the molecular structure of the antifreeze protein to understand how it works. Lead author Konrad Meister at Max Planck Institute for Polymer Research in Germany and his colleagues have traveled to the coldest places on Earth, including the Arctic and Antarctic, to collect antifreeze proteins from different sources. The protein they are examining in this study is the most active antifreeze protein on record, and it comes from a beetle in Northern Europe called Rhagium mordax.

“The antifreeze proteins have one side that is uniquely structured, the so-called ice-binding site of the protein, which is very flat, slightly hydrophobic and doesn’t have any charged residues,” Meister said. “But how this side is used to interact with ice is obviously very difficult to understand if you can’t measure an ice-protein interface directly.”

Now, for the first time, these unique biomolecules have been adsorbed to ice in the laboratory to get a closer look at the mechanisms that guide the interaction when antifreeze proteins are in contact with ice.

The researchers found that the protein’s corrugated structure, which holds channels of water in place, means that when these proteins touch ice, instead of freezing, the water molecules are altered to have a different hydrogen bond structure and orientation.

“Molecular-scale information is the key to understanding the function or the working mechanism of antifreeze proteins, and if we know that, then we can start making something cool that we as a society can benefit from.”

—Konrad Meister

Read the full story at AIP.

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Coated optical fibers as opto-mechanical sensors

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New model details Brillouin scattering interactions between light and sound waves in polyimide-coated fiber for detecting liquids outside the cladding boundary.

Since light carried by optical fibers cannot reach outside the inner core, it is difficult to use these cheap and flexible tools for the analysis of surrounding media. Fortunately, the same fibers also support the transfer of ultrasonic waves, and the interactions between light and sound waves can be exploited for probing the properties of liquids outside the protective coating.

Building on their previous research, Diamandi et al. extended their model of these light-ultrasound opto-mechanical sensors to include polyimide-coated fibers, which are readily available commercially. The coating gives the fiber some protection, and at the same time provides connectivity for the ultrasonic waves that actually perform the sensing task.

In their experiment, spectra of interaction between light and ultrasound were measured for stretches of fibers in air, ethanol and water. To push the experiment further, spatial mapping of liquids was carried out over a mile-long fiber that was coated in polyimide for its entire length.

Read the full story at AIP Scilight.

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Physicist Takes Cues from Artificial Intelligence

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NEWPORT NEWS, VA –  In the world of computing, there’s a groundswell of excitement for what is perceived as the impending revolution in artificial intelligence. Like the industrial revolution in the 19th century and the digital revolution in the 20th, the AI revolution is expected to change the way we live and work. Now, Cristiano Fanelli aims to bring the AI revolution to nuclear physics.

Fanelli, who is currently a postdoctoral researcher at the Massachusetts Institute of Technology, is the winner of the 2018 Jefferson Science Associates Postdoctoral Prize for his project to use artificial intelligence to optimize systems for nuclear physics research being carried out at the U.S. Department of Energy’s Thomas Jefferson National Accelerator Facility.

“It’s an exciting time to do nuclear and particle physics research with the artificial intelligence revolution happening now.”

—Cristiano Fanelli

Since 2015, Fanelli has been working on GlueX, an experiment that is being carried out as part of the 12 GeV upgrade to Jefferson Lab’s Continuous Electron Beam Accelerator Facility (CEBAF). Scientists in the GlueX collaboration aim to produce and study so-called exotic hybrid mesons. These particles are built of the same stuff as ordinary protons and neutrons: quarks bound together by the “glue” of the strong force. But the glue in these mesons behaves differently and may provide a window into how subatomic particles are built.

The GlueX collaboration is adding a new system to its existing equipment called DIRC, which stands for Detection of Internally Reflected Cherenkov light. The new system will help identify particles that are produced in experiments, such as protons, pions and kaons. This capability will allow researchers to infer the quark flavor content of exotic hybrid and conventional mesons produced in experiments.

The DIRC consists of a complex design of many components that must be aligned precisely for accurate particle identification. Fanelli is working on implementing Bayesian optimization to allow researchers to use computers to more quickly and accurately predict the optimum alignment for the components of the DIRC system.

Read the full story at JLAB.

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X-Ray Vision: Berkeley’s High-Speed Electrons Fuel Atomic-Scale Science

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BERKELEY, California—A group of eager writers attending the World Conference of Science Journalists 2017 stood on an upper platform at Berkeley’s Advanced Light Source (ALS) research lab. Under their feet, electrons raced at nearly the speed of light. Overhead, an iconic domed ceiling—the same ceiling under which Nobel laureate and nuclear scientist Ernest Lawrence invented the cyclotron—endowed a jumbled space full of laboratory pipes and instruments with the airy feel of a giant atrium.

As the journalists enjoyed their visit to Lawrence Berkeley National Laboratory on 29 October, magnets steered groups of electrons around a giant circle, 200 meters in circumference, and released light at 40 different openings. “Think of the electrons as cars with their headlights on,” said physicist Roger Falcone, director of ALS. “As they drive around, flashes of light come out each of those ports.”

Peering into molecules  

At the ends of each of the 40 light beams—in a range of wavelengths spanning the electromagnetic spectrum from infrared to both soft and hard X-rays—instruments perform experiments that depend on this constant flow of electrons. The relentless light penetrates materials and allows scientists to study the atoms and molecules inside. Each beam can be tuned to a different wavelength to reveal a particular element or molecule. Scientists use the beams to study everything from how the crystallographic structure of a new polymer reflects light rays to how a bacterium breathes in the absence of oxygen.

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The Dawn of Gallium Oxide Microelectronics

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WASHINGTON, D.C., February 6, 2018– Silicon has long been the go-to material in the world of microelectronics and semiconductor technology. But silicon still faces limitations, particularly with scalability for power applications. Pushing semiconductor technology to its full potential requires smaller designs at higher energy density.

“One of the largest shortcomings in the world of microelectronics is always good use of power: Designers are always looking to reduce excess power consumption and unnecessary heat generation,” said Gregg Jessen, principal electronics engineer at the Air Force Research Laboratory. “Usually, you would do this by scaling the devices. But the technologies in use today are already scaled close to their limits for the operating voltage desired in many applications. They are limited by their critical electric field strength.”

Transparent conductive oxides are a key emerging material in semiconductor technology, offering the unlikely combination of conductivity and transparency over the visual spectrum. One conductive oxide in particular has unique properties that allow it to function well in power switching: Ga2O3, or gallium oxide, a material with an incredibly large bandgap.

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Robotic Telescopes Enable Advanced Antarctic Observations

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Antarctica is more like interstellar space than any other place on earth. It is extremely cold‚ dry‚ calm‚ and extra dark with clear seeing to great cosmic distances. As a result‚ a telescope just a few meters tall near the South Pole can make observations as good as larger telescopes at more temperate locations and study the same objects that space satellites can study [1]‚ but at lower cost without sending telescopes into orbit [2]. But installing a telescope in Antarctica is not easy. It requires the use of a giant ice-breaker ship‚ track-wheeled tractors pulling huge storage containers‚ and a crew of woolen boot- and parka-clad “expedition astronomers” [3]. In 2005 a Chinese expedition became the first to reach the peak of the Antarctic ice cap‚ the highest point on the Antarctic Plateau 4093 meters above sea level. It was called Dome Argus‚ now known as Dome A.

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Mr. Universe. Lonely Hearts and Einstein in Love: The Personal Side of Science

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Mr. Universe. Lonely Hearts and Einstein in Love: The Personal Side of Science is a feature-length profile of former New York Times science editor and now self-dubbed “cosmic correspondent” Dennis Overbye. It details Overbye’s development as a science writer, his adventures at CERN, and his experience intimately covering the scientists behind major discoveries in cosmology from Alan Sandage to the Higgs Boson.

Read the full article (PDF).