Basic science

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.

Researchers from Rice University and the U.S. Department of Energy’s Oak Ridge National Laboratory have developed an additive-free, water-based ink made of lignin and cellulose, the fundamental building blocks of wood. The ink can be used to produce architecturally intricate wood structures via a 3D printing technique known as direct ink writing. The researchers focused on optimizing the composition of the ink by adjusting the ratio of lignin, cellulose nanofibers, and nanocrystals while maintaining the natural lignin-cellulose balance.

A Stanford University research team has used a 3D nanoprinting technique to produce Archimedean truncated tetrahedrons (ATTs). ATTs, micrometer-scale tetrahedrons with trimmed tips, have been theorized as having geometries that could produce phase-shifting materials, but are challenging to create in the real world. 3D printing could allow for precise control of particle shape and geometry to produce materials with novel physical properties.

Researchers at the Massachusetts Institute of Technology have found that neutrons can be made to cling to nanoparticles called quantum dots, which are made up of tens of thousands of atomic nuclei, held there by the strong force. Until this new work, nobody thought that neutrons might actually stick to the materials they were probing. “The fact that [the neutrons] can be trapped by the materials, nobody seems to know about that,” said Ju Li, one of the scientists involved in this study. “We were surprised that this exists.”

Researchers from the University of California, Berkeley, the U.S. Department of Energy’s Berkeley Lab, and the National Institute for Materials Science in Tsukuba, Japan, have taken the first atomic-resolution images and demonstrated electrical control of a chiral interface state – an exotic quantum phenomenon that could help researchers advance quantum computing and energy-efficient electronics.

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.

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.

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.

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.

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.