Category Physics

Schematic depiction of different energy terms contributing to the adsorption energy, and charge density difference of 2H-P after adsorption onto Cu(111) at 12.8 Angstrom separation. Credit: M. Müller/TU Munich

As we continue to shrink electronic components, top-down manufacturing methods begin to approach a physical limit at the nanoscale. A solution involves bottom-up self-assembly of molecular building blocks to build nanoscale devices.

Successful self-assembly is an elaborately choreographed dance, in which the attractive and repulsive forces within molecules, between each molecule and its neighbors, and between molecules and the surface that supports them, have to all be taken into account...

When cracks form, microbeads embedded in the material break open and cause a chemical reaction that highlights the damaged area. Credit: Image courtesy Nancy Sottos

Damage developing in a material can be difficult to see until something breaks or fails. A new polymer damage indication system automatically highlights areas that are cracked, scratched or stressed, allowing engineers to address problem areas before they become more problematic. The early warning system would be particularly useful in applications like petroleum pipelines, air and space transport, and automobiles – applications where one part’s failure could have costly ramifications that are difficult to repair.

“Polymers are susceptible to damage in the form of small cracks that are often difficult to detect...

In this image, a laser beam in an experiment propagates along the two-dimensional surface of a glass object shaped like an hourglass, curling once around the middle of the object. This is an example of an object with negative surface curvature (like a saddle, for example), in contrast to an object with positive surface curvature, such as a sphere. Credit: Vincent Schultheiß

To investigate the influence of gravity on the propagation of light, researchers usually have to examine astronomical length scales and huge masses. However, physicists have shown that there is another way. In a recent study, they find the answers to astronomical questions in the laboratory, shifting the focus to a previously underappreciated material property – surface curvature.

According to Einstein’s general theory...

The polymer sphere delivers the microRNA into cells already at the wound site, which turns the cells into bone repairing machines. Credit: Peter Ma

Scientists at the University of Michigan have developed a polymer sphere that delivers a molecule to bone wounds that tells cells already at the injury site to repair the damage. Using the polymer sphere to introduce the microRNA molecule into cells elevates the job of existing cells to that of injury repair by instructing the cells’ healing and bone-building mechanisms to switch on, said Prof Peter Ma.

Using existing cells to repair wounds reduces the need to introduce foreign cells – a very difficult therapy because cells have their own personalities, which can result in the host rejecting the foreign cells, or tumors...