A superchilled molecular gas nears the quantum limit of coldness

Long-sought molecular state promises to help scientists unveil quantum-scale chemistry. Long-sought molecular state promises to help scientists unveil quantum-scale chemistry.

To reconcile differing estimates, Masato Mori and his colleagues at the University of Tokyo combined observations and outputs from repeated runs of seven global climate models. They found that existing models tend to underestimate how strongly mid-latitude winter temperatures are affected by sea-ice loss in the remote Arctic. Over central Eurasia, almost half of the observed winter cooling trend for 1995 to 2014 can be clearly attributed to shrinking sea ice in the Barents and Kara seas, they conclude.

CLIMATE SCIENCE
Icy weather travels south as Arctic melts TECHNOLOGY The future's bright for 3D printing A fresh approach has increased both the speed and the reliability of a common method of 3D printing.
The technique known as stereolithographic printing builds each layer of a 3D object by projecting light through a window at the bottom of a vat of liquid resin. The light causes the resin to cure and solidify.
Mark Burns, Timothy Scott and their colleagues at the University of Michigan in Ann Arbor developed a method that uses two light sourcesone to solidify the resin, and a separate ultraviolet light to prevent resin from curing on the window's surface. The presence of a zone in which no unwanted solidification occurred allowed for efficient use of resins and boosted the speed of printing: objects such as embossed text a fraction of a millimetre across could be created in a single exposure, rather than layer-by-layer, as with conventional methods.
The combined use of two colours of light in 3D printing could be further expanded to create complex objects that integrate materials with different chemical and physical properties, the authors propose.

How a fever helps battle infection
A fever fights infection by helping immune cells to crawl along blood-vessel walls to attack invading microbes.
JianFeng Chen at the Shanghai Institute of Biochemistry and Cell Biology in China and his colleagues grew immune cells called T cells from mice, and raised the temperature of these cells from the normal mouse body temperature of 37 °C to 40 °C -the equivalent of a high fever. This heat triggered the T cells to start producing heatshock proteins (Hsps), which protect cells against stress.
The Hsps travelled to the inner surface of cells' outer membranes, where they bound to the tails of membrane proteins known as integrins. This process pulled integrins together, and the integrin sections jutting from the cells' outer surfaces formed complexes that stuck to bloodvessel walls. The formation of integrin complexes also triggered the migration of T cells to infection sites.
The authors then engineered mice to have a mutated form of integrin that couldn't bind to Hsps. When the team infected these animals with a diarrhoeacausing bacterium (Salmonella typhimurium), the mice died quickly from fever and infection. The findings suggest that therapies designed to raise levels of Hsps could help to fight infection. Bees also thrive in allotments, but because these community gardens occupy less than 1% of urban space, their positive impact on city pollinators is limited, the team found. Enlarging community gardens and encouraging weeds such as common daisies (Bellis perennis) and dandelions (Taraxacum officinale) to grow in public parks -easily achieved by mowing less often -could make communities of city pollinators more resilient, the authors suggest.

Stroke drug offers Alzheimer's hope
A drug that is being developed to treat people who have had a stroke also protects mice from some of the symptoms of Alzheimer's disease.
The drug, called 3K3A-APC, is a genetically modified version of a human blood protein that reduces inflammation and also helps prevent neurons and the cells that line the walls of blood vessels from degenerating. Berislav Zlokovic at the University of Southern California in Los Angeles and his colleagues tested whether it could also protect the brain from the toxic effects of the protein amyloid-β, which accumulates in the brain in Alzheimer's disease. For four months, mice that had been genetically altered to be susceptible to amyloid-β accumulation received daily injections of 3K3A-APC. The drug significantly lowered the brain levels of amyloid-β, and mice that had been treated fared as well as normal mice in memory tests at the end of the treatment period.
The scientists showed that 3K3A-APC prevents brain cells from making an enzyme called BACE1 that is required to produce amyloid-β (deposits pictured in yellow among neurons, blue, and microglial cells, violet). In a clinical trial for stroke treatment, the drug

Molecular gas feels the chill
After a decade of attempts in labs around the world, researchers have succeeded in making a gas of molecules so cold that they bump up against the limits of quantum physics.
Gases composed of individual atoms can be supercooled until quantum effects -the strange behaviours of very small particles -prevent the atoms from shedding more energy. But it's much harder to make this sort of gas using molecules, which are structurally more complex than atoms and, as a result, are more able to retain movement and energy.
Jun Ye and his team at the University of Colorado Boulder cooled millions of individual rubidium and potassium atoms until they approached the quantum limits of coldness. The researchers then used a magnetic field and light pulses to bind the atoms into a gas comprising tens of thousands of molecules at temperatures of 50 billionths of a kelvin, well below the threshold at which quantum effects dominate.
Studies of such molecular gases could provide fresh insight into chemistry at the quantum scale, the authors say.

Controversial law saves rare species
Populations of whales, seals, sea otters, manatees and sea turtles are bouncing back under the protection of the US Endangered Species Act, even after decades of habitat destruction and exploitation.
The act is designed to safeguard imperilled wildlife, but the administration of President Donald Trump views the law as an unnecessary burden and has introduced at least 75 bills seeking to weaken it.
To test the act's effectiveness, Abel Valdivia at the Center for Biological Diversity in Oakland, California, and his colleagues examined populations of 14 marine mammal species and 5 seaturtle species protected by the act. The team found that out of a total of 31 populations, 24 had recovered significantly since the animals were listed as endangered or threatened. Recovery was most likely for species that had received protection for more than 20 years. proved safe and was well tolerated, and the scientists say it holds potential as a treatment for early-stage Alzheimer's disease, when amyloid-β levels have not yet accumulated to permanently damaging levels.

J. Exp. Med. http://doi.org/czsp (2019)
The trend implies that vulnerable marine species in the United States survive largely because of the act's protection, the authors say.