Hair dyes help people express style and cover grey hair but often contain skin-irritating chemicals. Now, in ACS Sustainable Chemistry & Engineering, researchers report on a dye made from plant-derived compounds and zinc ions, a combination that turns hair a black-purple color. In initial tests, the cinnamon-scented dye stayed in human hair samples longer than a traditional hair dye did and deterred microbial growth, and in a preclinical animal trial, the dye didn’t irritate skin.

Fluorescent materials usually emit a single consistent color. They are typically made from made from dyes or metallic components. In contrast, researchers reporting in ACS Central Science have created carbon dots that can fluoresce in a range of colors under UV light, depending on the concentration and the liquid they’re in. The team incorporated the new carbon dots into plastic decorations and used them to create a data encryption system.

Tucked away inside a limestone cave in southeastern France lies some of the oldest artwork in existence. Known as Chauvet Cave, the site is so historically important — and fragile — that its location is kept secret and locked behind a huge steel door. And now, researchers reporting in ACS Omega have devised a technique to safely investigate these artworks and understand the natural varnish that has protected them for centuries. 

Endangered coho salmon and steelhead trout live and spawn in habitats surrounded by human activity, such as the San Francisco Bay area. During a recent storm, researchers found high levels of the tire-derived pollutant 6PPD-quinone in roadway outflows, creeks, and rivers. They report in ACS’ Environmental Science & Technology Letters that many samples exceeded levels considered fatal to juvenile salmon. Treating stormwater runoff and creating less toxic or non-toxic tire materials could make healthier environments.

One-quarter of the world’s data centers are located in areas where water demand exceeds supply for at least one month each year, according to a new global analysis. Researchers reporting in ACS’ Environmental Science & Technology mapped data center locations against available water resources and found that, under a future climate scenario, the proportion of facilities in water-stressed areas could rise to one-third.