Modified nitazenes, opioids 1,000 times stronger than morphine, show remarkably few adverse effects in rodents, renewing the potential of these drugs for pain relief.

The contrail clouds formed by jet engines contribute to global warming. In-flight measurements of the particles emitted and contrails produced by a passenger jet show that contrails are formed through different mechanisms, depending on the soot-emission level and the fuel composition, potentially reshaping our understanding of the climate impact of aviation.

Spiders and scorpions belong to a group called chelicerates, which are arthropods with pincers at the front of their head. Fossil evidence reveals how this group evolved.

A large-scale assessment of the reproducibility and robustness of 110 articles published in leading economics and political-science journals finds that more than 85% were computationally reproducible, and 72% of statistically significant results remained significant and in the same direction in robustness checks. About 25% of the evaluated articles contained non‑trivial coding errors.