Each week, The Daily’s Science & Technology section produces a roundup of the most exciting and influential research happening on campus or otherwise related to Stanford. Here’s our digest for the week of Oct. 11 — Oct. 17.

Nitrous oxide levels surpassed past climate projections over the last four decades

Emissions of nitrous oxide (commonly known as laughing gas) from human activity have increased by more than 30% over the past four decades, topping climate projections, a study published on Oct. 7 in “Nature” reported.

“We care doubly about nitrous oxide because it stays in the atmosphere a long time — typically a century or more after release,” earth system science professor Rob Jackson told Stanford Earth News.

Nitrous oxide is more potent than carbon dioxide, with one pound of nitrous oxide gas warming the atmosphere 300 times more than the same quantity of carbon dioxide.

The findings suggest the largest culprits of nitrous oxide emissions came from increased food production. Nitrous oxide is used in fertilizer, and manure produced by cattle ranching as cows also generates nitrous oxide.

“We need to turn the valve on emissions as quickly as possible,” Jackson said. Potential solutions to reducing emissions may include efficient nitrogen use in crops and consuming less beef.

Circadian rhythms affect Olympic athletes’ swim performance

Circadian rhythms can affect Olympic swimming performance, with athletes performing 0.39 seconds faster during the evening compared to the morning, a study published on Oct. 8 in “Scientific Reports” found.

“The magnitude of the effect is pretty big,” psychiatry postdoctoral research fellow Renske Lok told Stanford Medicine’s blog, SCOPE. “The difference was amazing, considering that athletes train at all times of the day.”

The team analyzed swimmers who reached the finals in the Athens, Beijing, London and Rio de Janeiro Olympic Games, and their findings suggest that the best Olympian finish times were at around 5 p.m.

Researchers are not sure of the reason for top performances in the evening.

“There are many possible factors,” Lok said. “One idea is core body temperature — it peaks in the evening. But it could also be a function of glucose, oxygen saturation levels, insulin, cortisol, testosterone — lots of things.”

Redesign of lithium-ion batteries improves efficiency

Scientists have re-engineered components to lithium-ion batteries that allow them to weigh less, become more energy-efficient and quench fires that may occur, a study published on Oct. 15 in “Nature Energy” reports.

“In our study, making the collector 80% lighter increased the energy density of lithium-ion batteries — how much energy they can store in a given weight — by 16-26%,” materials science and engineering professor Yi Cui told SLAC News. “That’s a big jump compared to the average 3% increase achieved in recent years.”

These changes to energy density allow batteries to store more energy, increasing the battery life. Additionally, the researchers used a fire retardant called triphenyl phosphate to embed components in the lithium-ion battery to reduce flammability.

These new redesigns can potentially address the issue of extending the driving range for electric vehicles and reducing fire hazard associated with fast-charging batteries.

Contact Derek Chen at derekc8 ‘at’ stanford.edu.