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

Scientists from the U.S. Department of Energy's Brookhaven National Laboratory and Pacific Northwest National Laboratory have used a combination of scanning transmission electron microscopy and computational modeling to get a closer look and deeper understanding of tantalum oxide. When this amorphous oxide layer forms on the surface of tantalum – a superconductor that shows great promise for making the "qubit" building blocks of a quantum computer – it can impede the material's ability to retain quantum information. "The key is to understand the interface between the surface oxide layer and the tantalum film, because this interface can profoundly impact qubit performance," said study co-author Yimei Zhu.

Scientists at the U.S. Department of Energy's Brookhaven National Laboratory have discovered that adding a thin layer of magnesium improves the properties of tantalum, a superconducting material that shows great promise for building qubits, the basis of quantum computers. The thin layer of magnesium keeps tantalum from oxidizing, improves its purity, and raises the temperature at which it operates as a superconductor. All three properties may increase tantalum's ability to hold onto quantum information in qubits.

Engineers at the University of California San Diego have developed an ultra-sensitive sensor made with graphene that can detect extraordinarily low concentrations of lead ions in water. The device achieves a record limit of detection of lead down to the femtomolar range, which is one million times more sensitive than previous sensing technologies. The device consists of a single layer of graphene mounted on a silicon wafer. The researchers enhanced the sensing capabilities of the graphene layer by attaching a linker molecule to its surface. 

Purdue University researchers have merged the power of advanced surfaces with thermal imaging algorithms to create a device that could open new frontiers in machine vision and autonomous systems. The device, called a Spinning MetaCam, could help classify materials and provide new possibilities for technologies in security, thermography, medical imaging, and remote sensing. The Spinning MetaCam contains metasurfaces – structured electromagnetic nanoscale surfaces crafted to behave like aqueducts for water, filtering and channeling light. Unlike traditional materials, which naturally bend, reflect, or absorb light, metasurfaces manipulate light’s intensity, spectrum, and polarization. 

A team of Rice University researchers has mapped out how flecks of two-dimensional (2D) nanomaterials move in liquid. The researchers used glowing soap to tag samples of hexagonal boron nitride nanosheets and make their motion visible. Videos of this motion allowed researchers to map out the trajectories of the samples and determine the relationship between their size and how they move. These findings could help scientists assemble macroscopic-scale materials with the same properties as their 2D counterparts. 

Using a DNA-based nanoparticle carrying viral proteins, researchers from the Massachusetts Institute of Technology (including the MIT Institute for Soldier Nanotechnologies), the Ragon Institute (of Massachusetts General Hospital, MIT, and Harvard University), and Washington University School of Medicine have created a vaccine that provokes a strong antibody response against SARS-CoV-2. The vaccine, which has been tested in mice, consists of a DNA nanoparticle that carries many copies of a viral antigen. Most previous work on this type of vaccine has relied on protein nanoparticles, but the proteins used in those vaccines tend to generate an unnecessary immune response that can distract the immune system from the target. In the mouse study, the researchers found that the DNA nanoparticle itself does not induce an immune response, allowing the immune system to focus its antibody response on the target antigen.

Researchers from Northwestern University, the Technical University of Denmark, and the Korea Advanced Institute of Science and Technology have addressed spatial resolution, electron scattering, and visibility limitations in closed-cell microchips based on silicon nitride. These closed-cell systems are widely used as “nanoscale reactors” inside high-vacuum electron microscopes. The researchers demonstrated that a beehive-like structure encapsulating heavily doped silicon beneath ultrathin silicon nitride substantially reduced membrane thickness, enabling the highest spatial resolution and spectral visibility thus far.

Engineers from the Massachusetts Institute of Technology (including the MIT Institute for Soldier Nanotechnologies) and the Army Research Laboratory have developed a new way to quickly test an array of metamaterial architectures and their resilience to supersonic impacts. Metamaterials are functional materials that contain unique microscale and nanoscale patterns or structures. The engineers suspended tiny, printed metamaterial lattices between microscopic support structures and then fired even tinier particles at the materials, at supersonic speeds. With high-speed cameras, the team captured images of each impact and its aftermath. Their work identified a few metamaterial architectures that are more resilient to supersonic impacts compared to their entirely solid, non-architected counterparts.

Researchers from the University of Miami, Missouri University of Science and Technology, and Cleveland State University have treated a chromium-containing nanoscale metal-organic framework to expand its pore size and surface area. The puffed-up metal-organic framework, created by the addition of concentrated acetic acid, held more ibuprofen or a chemotherapy drug than the original version and showed improved performance as a potential drug-delivery vehicle. 

Researchers from Yale University, the Korea Institute of Science and Technology, and the Chinese Academy of Sciences have reported new findings on the behavior of metallic glass and how these materials deform or respond to external stresses at very small size scales. Their finding of the size limits (approximately 100 nanometers) at which metallic glass does not deform provides insights that could lead to new ways of creating metallic glasses and provide researchers with a novel method to slowly grow metastable materials.