News from the NNI Community - Research Advances Funded by Agencies Participating in the NNI

In a first demonstration of "electron videography," researchers from the University of Illinois Urbana–Champaign and the Georgia Institute of Technology have captured a microscopic moving picture of the delicate dance between proteins and lipids found in cell membranes. The researchers achieved videography by combining a novel water-based transmission electron microscopy method with detailed, atom-level computational modeling. The water-based technique involves encapsulating nanometer-scale droplets in graphene so they can withstand the vacuum in which the microscope operates. "This is the first time we are looking at a protein on an individual scale and haven't frozen it or tagged it," said Aditi Das, one of the scientists involved in this study.

By analyzing the protein corona composition of gold nanoparticles, researchers from Michigan State University; the University of South Florida; Postnova Analytics Inc. in Salt Lake City, UT; and Clene Nanomedicine Inc. in Salt Lake City, UT, have explained how the protein corona helps to treat neurodegenerative diseases. The nanoparticles pass through the gastrointestinal tract and enter the body's circulatory system, where they interact with, and become coated by, blood proteins and other biomolecules. This forms the protein corona. "Our research shows that these gold nanocrystals, manufactured using a novel method to form specific structures and without surfactants, can form a distinct protein corona that facilitates access to brain tissue," says Morteza Mahmoudi, one of the scientists involved in this study.

By harnessing the weak van der Waals forces that bind layers of 2D materials together, researchers from Washington University in St. Louis; Ajou University in Suwon, South Korea; Chonnam National University in Gwangju, South Korea; and Sungkyunkwan University in Suwon, South Korea, have demonstrated a nondestructive method to comprehensively map the grain structure and crystal orientations of 2D materials. The key innovation lies in using a filter made from a single layer of high-quality, single-crystal graphene with a known orientation as a reference. An unknown sample is placed on top of this filter to create a temporary stack. By shining laser light on the stack and collecting the Raman signal, the researchers can map out the location and orientation of individual grains in the sample with sub-micron resolution. 

Electrostatic capacitors enable ultrafast charging and discharging, providing energy storage and power for smartphones, laptops, medical devices, and car electronics. But the ferroelectric materials used in these capacitors have significant energy loss, making it difficult to provide high energy storage capability. Now, researchers at Washington University in St. Louis; the Massachusetts Institute of Technology; Yonsei University in Seoul, South Korea; Sungkyunkwan University in Suwon, South Korea; Ulsan National Institute of Science and Technology in South Korea; and the Korea Institute of Science and Technology in Seoul have developed novel 2D/3D/2D heterostructures that can minimize energy loss while preserving the advantageous material properties of ferroelectric 3D materials. Their approach sandwiches 2D and 3D materials in atomically thin layers with carefully engineered chemical and nonchemical bonds between each layer. 

Researchers at the University of Illinois Urbana-Champaign, Seoul National University in South Korea, and the National Institute for Materials Science in Tsukuba, Japan, have developed a method to visualize the thermally induced rearrangement of two-dimensional (2D) materials, atom-by-atom, from twisted to aligned structures, using transmission electron microscopy. The researchers observed a new and unexpected mechanism for this rearrangement process. "People usually think of the two layers like having two sheets of paper twisted 45° to each other. To get the layers to go from twisted to aligned, you would just rotate the entire piece of paper," said Yichao Zhang, one of the scientists involved in this study. "But what we found, actually, is it has a nucleus – a localized nanoscale aligned domain – and this domain grows larger and larger in size.”

By using simulations on a supercomputer at the University of Texas at Austin (UT Austin) and a small transformer powered by UT Austin's one megawatt micro grid, researchers from UT Austin, the University of Maryland, Rensselaer Polytechnic Institute in Troy, NY, and the U.S. Department of Agriculture’s Forest Products Laboratory in Madison, WI, have developed a solution to address the overheating of grid transformers. The researchers created a high thermal conductivity paper using nanoparticles of boron nitride and tested it on the small transformer. "Our results indicate that if the thermal conductivity is increased by a few times using the engineered paper, the hotspot temperature inside a transformer can be reduced by between 5 to 10 °C," said Robert Hebner, one of the scientists involved in this study. "In most conditions, that should be enough to double or triple the life of the transformer."

Using a pair of sensors made from carbon nanotubes, researchers from the Massachusetts Institute of Technology (MIT), the Singapore-MIT Alliance for Research and Technology, and the National University of Singapore have discovered signals that reveal when plants are experiencing stresses, such as heat, light, or attack from insects or bacteria. The researchers found that plants produce hydrogen peroxide and salicylic acid (a molecule similar to aspirin) at different timepoints for each type of stress, creating distinctive patterns that could serve as an early warning system. Farmers could use these sensors to monitor potential threats to their crops, allowing them to intervene before the crops are lost, the researchers said.

Researchers from the Massachusetts Institute of Technology, Universitat de Girona in Spain, and Universidade do Porto in Portugal have shown that they can prevent cracks from spreading between layers in a composite material by depositing chemically grown forests of carbon nanotubes between the composite layers. The tiny, densely packed fibers grip and hold the layers together, like ultrastrong Velcro, preventing the layers from peeling or shearing apart. In experiments with an advanced composite, known as a thin-ply carbon fiber laminate, the team showed that layers bonded that way improved the material's resistance to cracks by up to 60% compared with composites with conventional polymers.

Duke University researchers have captured close-ups of corrosion in action. They zapped nanocrystals of a catalyst called ruthenium dioxide with high-energy radiation and then watched the changes that occurred. To take pictures of such tiny objects, they used a transmission electron microscope, which shoots a beam of electrons through the nanocrystals (suspended inside a thin pocket of liquid) to create time-lapse images of the chemistry taking place at 10 frames per second. The result: close-ups of virus-sized crystals, more than a thousand times finer than a human hair, as they get oxidized and dissolve into the acidic liquid around them.

Scientists at Princeton University have, for the first time, successfully visualized the elusive Wigner crystal – a strange form of matter made only of electrons that assemble into a crystal-like formation of their own (without the need to coalesce around atoms). The scientists cooled the sample down to extremely low temperatures—just a fraction of a degree above absolute zero—and applied a magnetic field perpendicular to the sample, which created a two-dimensional electron gas system between two thin layers of graphene – a two-dimensional material made of carbon atoms. “Our work provides the first direct images of this crystal,” said Yen-Chen Tsui, one of the scientists involved in this study. “We proved the crystal is really there and we can see it.”