Many biologically important molecules change shape when stimulated by UV radiation. Although this property can also be found in some drugs, it is not yet well understood. Using an innovative technique, an international team involving researchers from Goethe University Frankfurt, the European XFEL in Schenefeld and the Deutschen Elektronen-Synchrotron DESY in Hamburg has elucidated this ultra-fast process, and made it visible in slow motion, with the help of X-ray light. The method opens up exciting new ways of analyzing many other molecules.

The study is published in the journal Nature Communications.

“We investigated the molecule 2-thiouracil, which belongs to a group of pharmaceutically active substances based on certain DNA building blocks, the nucleobases,” says the study’s last author Markus Gühr, the head of DESY’s free-electron laser FLASH and Professor of Chemistry at University of Hamburg. 2-thiouracil and its chemically related active substances have a sulfur atom, which gives the molecules its unusual, medically relevant properties.

The discovery of a mini aurora above a light-emitting polymer material reveals an electron-ejection process that might be useful in field-emission displays and material fabrication.

Auroras occur in the night sky when charged solar-wind particles, such as protons and electrons, are deflected by Earth’s magnetic field and interact with molecules in the atmosphere. Researchers have now found an aurora-like emission coming from a light-emitting polymer [1]. The surprising display consisted of flashes of green light above the polymer surface. The researchers explained the emission as the result of electrons being ejected from the polymer and interacting with a vapor of organic molecules. The discovery suggests that these polymers might be useful as electron emitters for applications such as spectroscopy, medical technology, and lithography.

Jun Gao from Queen’s University in Canada is amazed by auroras, and he’s even gone out on cold nights to look for them. But he was not prepared for the aurora that showed up in his lab two years ago. He and his student at the time, Dongze Wang, were testing failure modes for polymer light-emitting electrochemical cells, or PLECs, used in light sources and display devices. These cells are organic semiconductors that are electrochemically doped on one side to have excess electrons (making an n-type semiconductor) and on the other side to have electron deficiencies, or holes (making a p-type semiconductor). Electrons crossing the p – n boundary can fill holes and produce red light.

Eye injuries that damage the cornea are usually irreversible and cause blindness. But a new clinical trial has repaired this damage in patients thanks to a transplant of stem cells from their healthy eyes.

The cornea is the outer layer of the eye, which focuses light towards the retina. Since it’s on the frontline of potential hazards from the outside world, the cornea features a population of limbal epithelial stem cells, which repair minor damage to keep the surface smooth and functional.

Unfortunately, injuries like thermal or chemical burns can damage the cornea beyond the capability of these resident stem cells. There’s not much else that can be done – even a cornea transplant won’t take hold if the damage is too severe.