(Funded by the U.S. Department of Energy and the U.S. National Science Foundation)
Scientists at Penn State have developed a new design for thermogels – materials that can be injected as a liquid and turn into a solid inside our bodies – that further improves these materials’ properties. The newly designed thermogels are made with nanoparticles that have sticky spots, similar to arms reaching out and giving the nanoparticles places to connect with one another and form a structure. The method may be especially appealing for soft tissue reconstruction, in which case thermogels could serve as structures that provide a framework for cells to stick to and form new, healthy tissue.

(Funded by the U.S. National Science Foundation and the U.S. Department of Energy)
When materials are created on a nanometer scale, even the thermal energy present at room temperature can cause structural ripples. How these ripples affect the mechanical properties of these thin materials can limit their use in electronics and other key systems. Now, using a semiconductor manufacturing process, researchers from Binghamton University, Harvard University, Princeton University, Penn State, and the U.S. Department of Energy’s Argonne National Laboratory have created alumina structures that are 28 nanometers thick on a silicon wafer with thermal-like static ripples, and then tested these ripples with lasers to measure their behavior. The results match with theories proposed about such structural ripples.

(Funded by the U.S. National Science Foundation and the U.S. Department of Defense)
Engineers at Harvard University have created a bilayer metasurface made of two stacked layers of titanium dioxide nanostructures. Almost a decade ago, the engineers had unveiled the world’s first visible-spectrum metasurfaces – ultra-thin, flat devices patterned with nanostructures that could precisely control the behavior of light and enable applications in imaging systems, augmented reality, and communications. But the single-layer nanostructure design has been in some ways limiting. For example, previous metasurfaces put specific requirements on the manipulation of light’s polarization in order to control the light’s behavior. Using the facilities of the Center for Nanoscale Systems at Harvard, the engineers came up with a fabrication process for freestanding, sturdy structures of two metasurfaces that hold strongly together but do not affect each other chemically.

(Funded by the U.S. Department of Energy and the U.S. National Science Foundation)
The shape of nanoparticles depends on the choice of solvent and temperature during their growth. But the tiny seed particles that form first and that guide the formation of final nanoparticle shapes are too small to measure accurately. With the help of a supercomputer, Penn State researchers have developed computer simulations to model seed particles with 100 to 200 atoms. They found that the shapes of the tiny particles depend on the solvent composition and temperature in unexpected ways. Surprisingly, in some cases the shape of the seed particle changes dramatically when only a single atom is added or removed.

(Funded by the U.S. National Science Foundation and the National Institute of Standards and Technology)
The fractional quantum Hall effect arises when electrons in two-dimensional materials are subject to a strong perpendicular magnetic field at very low temperatures. Researchers from George Mason University, Brown University, and the National Institute of Standards and Technology have shown that fractional quantum Hall states could be better detected using thermopower measurements than with conventional electrical resistivity. (Thermopower is an electrical voltage generated when charge carriers move from the hot side to the cold side of a conducting or semiconducting material.) The researchers performed thermopower measurements on bilayer graphene and observed new fractional quantum Hall states, which had not been previously reported.