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

For the first time, engineers at Northwestern University have created a double layer of atomically flat borophene, a feat that defies the natural tendency of boron to form non-planar clusters beyond the single-atomic-layer limit. Although known for its promising electronic properties, borophene -- a single-atom-layer-thick sheet of boron -- is challenging to synthesize. Unlike its analog two-dimensional material graphene, which can be peeled away from innately layered graphite using something as simple as scotch tape, borophene cannot merely be peeled away from bulk boron. Instead, borophene must be grown directly onto a substrate.

Scientists at the U.S. Department of Energy's Ames Laboratory have discovered that an unwanted byproduct of their experiments is a high-quality substance sought after by scientists researching layered materials. The scientists’ focus is magnesium diboride. But they also produce hexagonal boron nitride, a highly sought-after and difficult-to-obtain insulating material for scientists researching graphene, the 2D layered semimetal that was first discovered in 2010.

Optoelectronics, a technology that gives off, detects, or controls light, is used everywhere in modern electronics and includes light-emitting diodes and solar cells. Within these devices, the movement of excitons (pairs of negative electrons and positive holes) determines how well the device performs. Until now, the distance that excitons could travel in conventional optoelectronic systems was around 30-70 nanometers, and there was no way to directly image how the excitons move. Now, a team of researchers from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory and the Swiss Federal Institute of Technology Lausanne has designed and made a nanocrystal system in which excitons can move a record distance of 200 nanometers, an order of magnitude larger than what was previously possible.

Scientists from the U.S. Department of Energy’s Brookhaven National Laboratory, the University of Pennsylvania, the University of New Hampshire, the Chinese University of Hong Kong, Stony Brook University, and Columbia University have detected electronic and optical interlayer resonances in two different configurations of bilayer graphene—the two-dimensional (2D), atom-thin form of carbon. They found that twisting one of the graphene layers by 30 degrees relative to the other, instead of stacking the layers directly on top of each other, shifts the resonance to a lower energy. From this result, they deduced that the distance between the two layers increased significantly in the twisted configuration, compared to the stacked one. 

Researchers from the University of Texas at Austin, in collaboration with the U.S. Army Research Lab, are analyzing new materials for electrical insulation that can remove heat more effectively compared to today's insulation. They provide a critical review and perspectives of new nanocomposite materials from an engineering and reliability perspective.

MIT scientists have built a system containing alternating semiconductor layers that could potentially protect quantum bits (qubits) from degrading into regular bits by realizing a phenomenon called many-body localization (MBL). Three-nm-thick alternating layers of aluminum arsenide and gallium arsenide were used to create a microscopic “lasagna” 600 layers deep, with "nanodots," 2-nm particles of erbium arsenide, dispersed between the layers. The identification of MBL signatures provides new opportunities to study quantum phenomena, and potential applications range from thermal storage to quantum computing.

Engineers at Texas A&M University have designed a 3D-bioprinted model of a blood vessel that mimics its state of health and disease. Current bioinks used to print blood vessels in 3D are unable to deposit a high density of living cells into complex 3D architectures, making them less effective. To overcome these shortcomings, the engineers developed a new nanoengineered bioink to print 3D, anatomically accurate, multicellular blood vessels. Their approach offers improved real-time resolution for both macro-structure and tissue-level micro-structure, which is currently not possible with available bioinks.

An interdisciplinary team of researchers from the University of North Carolina at Charlotte, North Carolina State University, Columbia University, and Frederick National Laboratory for Cancer Research utilized DNA for the precise assembly of quantum dots into larger three-dimensional scaffolds. The unique optical properties of these semiconductor nanoparticles have been previously utilized in several applications, including for imaging and biosensing. 

Scientists from Rice University and Tokyo Metropolitan University have woven custom-made #nanotube fibers into enhanced, flexible #cotton #fabric that turns #heat into enough #energy to power a light-emitting diode (#LED). The researchers note that the nanotube-enhanced materials could become building blocks for fiber and #textile #electronics and energy harvesting. The materials can act as both #thermoelectric generators and heat sinks to actively cool sensitive electronics with high efficiency.

Immunotherapies help boost the immune system's ability to fight off cancer cells. Immune checkpoints are regulators of the immune system, but some types of cancer circumvent these checkpoints, allowing cancerous cells to avoid detection and continue to spread. Immune checkpoint blockade (ICB) is a newer therapy that can essentially "release the brakes" on the immune system and help the body fight back. Researchers at the University of Arizona Health Sciences have created the first nanotherapeutic platform of its kind to enhance the ability of camptothecin, a chemotherapeutic agent, to synergize with ICB therapies, making them more effective against aggressive tumors.