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

Researchers from the University of California, Santa Barbara, The Ohio State University, and the University of Hong Kong have, for the first time, characterized the thermoelectric properties of high-quality cadmium arsenide thin films. The researchers created three high-quality films of varying thicknesses – 950 nanometers (nm), 95 nm, and 25 nm – and found that the thinner the material, the higher the thermoelectric sensitivity, resulting in more voltage in response to a temperature gradient, a response enhanced by seven times compared to the state-of-the-art material. These effects were found at near-zero temperatures, so although these thin films can't be deployed for room-temperature applications, they could be useful in cryogenic environments.

Researchers from the U.S. Department of Energy’s Los Alamos National Laboratory (LANL) and Lawrence Berkeley National Laboratory (LBNL) and Seoul National University in South Korea have developed a way to directly measure such materials' thermal expansion coefficient, the rate at which the material expands as it heats. Due to the thinness of two-dimensional materials, until now, measuring their thermal expansion could only be accomplished indirectly or with the use of a support structure called a substrate. The work was conducted at the Molecular Foundry, a user facility at LBNL, and the Center for Integrated Nanotechnologies, a user facility at LANL and the U.S. Department of Energy’s Sandia National Laboratories.

Engineers at the University of California San Diego have developed a pill that releases microscopic robots, or microrobots, into the colon to treat inflammatory bowel disease (IBD). The experimental treatment, given orally, has shown success in mice. It significantly reduced IBD symptoms and promoted the healing of damaged colon tissue without causing toxic side effects. The microrobots are composed of inflammation-fighting nanoparticles chemically attached to green algae cells. The nanoparticles absorb and neutralize pro-inflammatory cytokines in the gut, and the green algae distribute the nanoparticles throughout the colon, accelerating cytokine removal to help heal inflamed tissue.

Researchers from the U.S. Department of Energy's Argonne National Laboratory and Universidad de Zaragoza in Spain have discovered that how calcite is synthesized, or chemically transformed, can dramatically change the internal structure of individual mineral particles. The scientists compared the external shape and internal structure of calcite particles grown by two synthesis approaches. For one synthesis approach, calcite crystals were grown slowly, and a 3D map of the crystal structure inside the calcite particles showed the orderly, repeating patterns scientists expected to see. Using the other synthesis approach, crystals were grown very quickly. This time, a more complex internal structure was seen. Each perfectly shaped calcite crystal was composed of countless nanosized crystalline fragments, or defects. 

Researchers from the University of Michigan, the U.S. Department of Energy’s SLAC National Accelerator Laboratory, Carnegie Mellon University, and Harvard University have discovered that the electrical conductivity of three layers of graphene, in a twisted stack, is similar to that of “magic angle” bilayer graphene. Stacking three layers of graphene introduced an additional twist angle, creating non-repeating patterns, at small-angle twists – unlike bilayer graphene which forms repeating patterns. “This discovery makes fabrication easier, avoiding the challenge of ensuring the precise twist angle that bilayer graphene requires,” said Mohammad Babar, the first author of the study.

University of Missouri researchers have developed a novel 3D printing and laser process to manufacture multi-material, multi-layered sensors, circuit boards, and even textiles with electronic components. The researchers built a machine that has three different nozzles: one nozzle adds ink-like material, another uses a laser to carve shapes and materials, and a third nozzle adds functional materials to enhance the product’s capabilities. The manufacturing process starts by making a basic structure with a regular 3D printing filament. Then, a laser converts some parts into laser-induced graphene. Finally, more materials are added to enhance the functional abilities of the product.

Until now, scientists believed there was a limit to the sharpness of the separation of solutes in water or other fluids that they could achieve with a porous membrane, not only because of variations in pore size but also because of a phenomenon called hindered transport – the internal resistance of the fluid as a solute tries to go through a pore. Now, researchers from the U.S. Department of Energy’s Argonne National Laboratory and the University of Chicago have shown that by using an isoporous membrane, in which all the pores are the same size (approximately 10 nanometers), and by giving the solutes multiple chances to get through the pores, it is possible to surmount hindered transport limitations. 

Researchers from Cornell University have used solubility rather than entropy to overcome thermodynamic constraints and create high-entropy oxide nanocrystals at lower temperatures. High-entropy materials are formed by mixing five or more elements within the structure of a crystal.

Scientists from the University of Utah have found a way to deliver drugs to a specific area of the body by using nanocarriers activated by ultrasound waves. The nanocarriers are minuscule droplets with a hollow outer shell composed of polymer molecules. Within the shell is an inner core of hydrophobic molecules that are mixed with an equally hydrophobic drug of interest. To release the drug, the researchers send ultrasound waves, which are thought to cause the hydrophobic molecules to expand, stretching out the droplet's shell. The drug then diffuses out to the cells, organs, or tissues where it is required.

Researchers from the University of California San Diego and Duke University have engineered nanosized cubes that spontaneously form a two-dimensional checkerboard pattern when dropped on the surface of water. Each nanocube is composed of a silver crystal with a mixture of hydrophobic (oily) and hydrophilic (water-loving) molecules attached to the surface. When a suspension of these nanocubes is introduced to a water surface, they arrange themselves such that they touch at their corner edges. This arrangement creates an alternating pattern of solid cubes and empty spaces, resulting in a checkerboard pattern.