Light-emitting diodes (LEDs), semiconductor-based devices that emit light when an electric current flows through them, are key building blocks of numerous electronic devices. LEDs are used to light up smartphone, computer, and TV displays, as well as light sources for indoor and outdoor environments.

Past studies consistently observed a decline in the performance and efficiency of LED devices based on two-dimensional (2D) materials at high current densities. This loss of efficiency at high current densities has been linked to high levels of interaction between excitons, which cause a process known as exciton-exciton annihilation (EEA).

Essentially, the properties of some 2D materials...

Scientists using observations from NASA’s Neil Gehrels Swift Observatory have discovered, for the first time, the signal from a pair of monster black holes disrupting a cloud of gas in the center of a galaxy.

“It’s a very weird event, called AT 2021hdr, that keeps recurring every few months,” said Lorena Hernández-García, an astrophysicist at the Millennium Institute of Astrophysics, the Millennium Nucleus on Transversal Research and Technology to Explore Supermassive Black Holes, and University of Valparaíso in Chile. “We think that a gas cloud engulfed the black holes. As they orbit each other, the black holes interact with the cloud, perturbing and consuming its gas. This produces an oscillating pattern in the light from the system.”

A paper about AT 2021hdr, led by Hernán...

Researchers at Baylor College of Medicine, Stanford University School of Medicine and collaborating institutions report in the journal Cell the discovery of BHB-Phe, a novel compound produced by the body that regulates appetite and body weight through interactions with neurons in the brain.

Until now, BHB has been known as a compound produced by the liver to be used as fuel. However, in recent years, scientists have found that BHB increases in the body after fasting or exercise, prompting interest in investigating potential beneficial applications in obesity and diabetes.

In the current study, the team at Stanford University led by co-corresponding author Dr. Jonathan Z. Long, associate professor of pathology, discovered that BHB also participates in another metabolic pathway...

An international research team has for the first time designed realistic photonic time crystals–exotic materials that exponentially amplify light. The breakthrough opens up exciting possibilities across fields such as communication, imaging and sensing by laying the foundations for faster and more compact lasers, sensors and other optical devices.

“This work could lead to the first experimental realization of photonic time crystals, propelling them into practical applications and potentially transforming industr...