Physics Today Daily Edition
BBC: Shape-shifting materials typically require an external trigger to initiate the shape change. Now Sergei Sheiko of the University of North Carolina at Chapel Hill and his colleagues have developed a polymer in which the transformation occurs at a predetermined time with no outside stimuli necessary. The researchers created a polymer with two types of chemical bonds: permanent and dynamic. The permanent bonds define the material's final shape; the dynamic bonds control how quickly the material can reach that shape, depending on the strength and concentration of the bonds. The timing precision is limited to a scale of minutes to hours, but that may be sufficient for the material to be used for applications such as drug delivery.
National Geographic: A study in Nature that presents the most complete reconstruction so far of 2 million years of global sea-surface temperatures has been both praised and panned by scientists not involved in the work. The scientists say the reconstructed data will play an important role in establishing a clear understanding of Earth's climate history. But it's the conclusion that the paper's author draws—that even if all further greenhouse gas emissions were capped, global temperatures could still rise by up to 7 °C—that has received harsh criticism. The author, Carolyn Snyder, who is now at the US Environmental Protection Agency, says that the prediction was not the primary goal of the work; she was just examining what the relationship between sea-surface temperature and atmospheric carbon dioxide levels might mean in the future. But other scientists argue that she has incorrectly extrapolated the future relationship by basing it on past climate changes that were caused by factors other than greenhouse gases.