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There’s still plenty of room at the bottom to generate piezoelectricity. Engineers at Rice University and their colleagues are showing the way.

A new study describes the discovery of piezoelectricity—the phenomenon by which mechanical energy turns into electrical energy —across phase boundaries of two-dimensional materials.

The work led by Rice materials scientists Pulickel Ajayan and Hanyu Zhu and their colleagues at Rice’s George R. Brown School of Engineering, the University of Southern California, the University of Houston, Wright-Patterson Air Force Base Research Laboratory and Pennsylvania State University appears in Advanced Materials.

A new experiment shows that spin currents can be controlled electrically in the room temperature multiferroic material.

In an example of the adage “everything old is new again,” MIT engineers report a new discovery in semiconductors, well-known materials that have been the focus of intense study for over 100 years thanks to their many applications in electronic devices.

The team found that these important materials not only become much stiffer in response to light, but the effect is reversible when the light is turned off. The engineers also explain what is happening at the atomic scale, and show how the effect can be tuned by making the materials in a certain way—introducing specific defects—and using different colors and intensities of light.

“We’re excited about these results because we’ve uncovered a new scientific direction in an otherwise very well-trod field. In addition, we found that the phenomenon may be present in many other compounds,” says Rafael Jaramillo, the Thomas Lord Associate Professor of Materials Science and Engineering at MIT and leader of the team.

In late May, a collaborative study, led by Kailash Suhu, was published claiming that they had managed to identify the first ever isolated black hole, identified by shorthand as OB11046. While by itself, this discovery presents no new information with regards to their nature, it highlights the staggering progress we’ve made in recent years in detecting these bodies.

Previously, black hole detection was very much limited by the fact that they do not emit, nor reflect any detectable electromagnetic radiation. As such, astronomers were only able to infer their presence via two mechanisms.

The first is by tracking the orbits of nearby celestial bodies and observe whether their motion can be modelled by the forces experienced by their neighbours. Any unusual motion can usually be explained by a nearby black hole contributions. The second requires the black hole to form an accretion disk. As matter is caught in the intense gravitational field, it orbits the black hole and is accelerated to intense velocities, causing the material to emit certain wavelengths of high energy electromagnetic radiation, such as x-rays.

We’ve recently heard about efforts to replace some of the aggregate used in concrete with crumbled used tires. Now, scientists have succeeded in producing good quality concrete in which all of the aggregate has been replaced with tire particles.

In recent years, we’ve heard about efforts to replace some of the aggregate used in concrete with crumbled used tires. Now, however, scientists have succeeded in producing good quality concrete in which all of the aggregate has been replaced with tire particles.

Concrete consists of three parts: water, a cement which binds everything together, and an aggregate such as sand or gravel. That aggregate has to be mined from the ground, and is actually now in short supply in many parts of the world.

Continue reading “Scientists create quality concrete with 100% tire-rubber aggregate” »

The findings could aid the design of new multiphase materials for clean energy applications and beyond.

MIT researchers have developed a method for 3D printing materials with tunable mechanical properties, which can sense how they are moving and interacting with the environment. The researchers create these sensing structures using just one material and a single run on a 3D printer.

To accomplish this, the researchers began with 3D-printed lattice materials and incorporated networks of air-filled channels into the structure during the printing process. By measuring how the pressure changes within these channels when the structure is squeezed, bent, or stretched, engineers can receive feedback on how the material is moving.

These lattice materials are composed of single cells in a repeating pattern. Changing the size or shape of the cells alters the material’s mechanical properties, such as stiffness or hardness. For instance, a denser network of cells makes a stiffer structure.

A sheet of magic-angle twisted bilayer graphene can host novel topological phases of matter, a study has revealed.

Magic-angle twisted graphene, first discovered in 2018, is made from two sheets of graphene (a form of carbon consisting of a single layer of atoms in a honeycomb-like lattice pattern), layered atop one another, with one sheet twisted at precisely 1.05 degrees with respect to the other. The resulting bilayer has unusual electronic properties: for example, it can be made into an insulator or a superconductor depending on how many electrons are added.

The discovery launched a new field of research into magic-angle twisted graphene, known as “twistronics.” At Caltech, Stevan Nadj-Perge, assistant professor of applied physics and materials science, has been among the researchers leading the charge: in 2019, he and his colleagues directly imaged the electronic properties of magic-angle twisted graphene at atomic-length scales; and in 2020, they demonstrated that superconductivity in twisted bilayer graphene can exist away from the magic angle when coupled to a two-dimensional semiconductor.