(Funded by the National Science Foundation)
Researchers from the University of Nebraska-Lincoln and South Dakota School of Mines and Technology are exploring the physical properties of two-dimensional materials called MXenes. Previous research by the Nebraska team on other MXene materials revealed their n-type (electron-rich) character and decreased conductivity in response to light. In contrast, the new material is the first MXene with demonstrated p-type (electron-deficient) property and increasing conductivity under illumination. “Previously studied MXenes were all n-type, but now we demonstrate the first p-type MXene,” said Alexander Sinitskii, the scientist who led this study. “This should enable complex structures where complementary MXenes are used together to achieve new electronic functionalities.”The researchers performed experiments at the Nebraska Center for Materials and Nanoscience, a user facility that is part of the National Science Foundation-funded National Nanotechnology Coordinated Infrastructure.

(Funded by the U.S. Department of Energy, U.S. Department of Defense, and the National Science Foundation)
Researchers from the University of Chicago; the University of California, Berkeley; Northwestern University; the University of Colorado Boulder; and the U.S. Department of Energy’s Argonne National Laboratory have developed a new technique for growing quantum dots – nanocrystals used in lasers, quantum light-emitting diode (QLED) televisions, and solar cells. The researchers replaced organic solvents typically used to create quantum dots with molten salt – literally superheated sodium chloride of the type sprinkled on baked potatoes. “Sodium chloride is not a liquid in your mind, but assume you heat it to such a crazy temperature that it becomes a liquid … [N]obody ever considered these liquids as media” for the synthesis of quantum dots, said Dmitri Talapin, one of the scientists involved in this study.

(Funded by the National Science Foundation and the U.S. Department of Defense)
Researchers from Penn State, the Massachusetts Institute of Technology (MIT) (including @MIT_ISN), and North Carolina Agricultural and Technical State University have discovered a different version of the Hall effect, called the nonreciprocal Hall effect, which, unlike the conventional Hall effect, does not require a magnetic field. In particular, in this case, the Hall voltage is proportional to the square of the current instead of being proportional to the current. Also, unlike the conventional Hall effect, which is driven by a force induced by the magnetic field, the nonreciprocal Hall effect arises from flowing electrons interacting with platinum nanoparticles. This discovery could lead to applications in the development of quantum communication and harvesting of energy via radio frequencies.

(Funded by the National Institutes of Health and the National Science Foundation)
Researchers from Carnegie Mellon University and the Indian Institute of Technology Bombay in Mumbai, India, have linked the immune response caused by lipid nanoparticles to their lipid chemistry. They found that some lipid structures bind strongly to receptors and others bind weakly. The strong interactions trigger the receptor and ultimately the immune response. The findings will help engineers tailor immune responses when designing lipid nanoparticles for drug delivery. “For vaccines, we might want something that’s more immunogenic, so that the vaccine responds better,” said Namit Chaudhary, one of the scientists involved in this study. “But if we are delivering something to the brain or the liver, for example, we might not want to evoke substantial immune responses that might cause toxicity.”

(Funded by the National Science Foundation and the U.S. Department of Energy)
Researchers from New York University, the U.S. Department of Energy’s Brookhaven National Laboratory, the Korea Advanced Institute of Science and Technology, and the National Institute for Materials Science in Tsukuba, Japan, have pioneered a new technique to identify and characterize atomic-scale defects in a two-dimensional (2D) material called hexagonal boron nitride. The team was able to detect the presence of individual carbon atoms replacing boron atoms in this material. “In this project, we essentially created a stethoscope for 2D materials,” said Davood Shahrjerdi, one of the researchers involved in this study. “By analyzing the tiny and rhythmic fluctuations in electrical current, we can ‘perceive’ the behavior of single atomic defects.”