French press physics and a Barbie bounty

A lava-java connection

For the coffee snobs among us, the French press is a delightful way to enjoy a morning java. Add grounds to the pitcher, pour hot water over them, and gently push the plunger, forcing the spent grounds down and the fragrant brew up.

But there’s also science brewing in that carafe, says Fabian Wadsworth. He’s a volcano expert at Durham University who as part of a team of researchers figured out an equation to describe the force needed to push down a French press plunger based on the speed of the plunger and the amount of coffee grounds (Am. J. Phys. 2021, DOI: 10.1119/10.0004224).

Fluids are constantly moving between the solid and porous pieces of Earth’s crust, Wadsworth tells Newscripts. The motion of liquid coffee around and through its grounds is a similar physical process.

“The question is: If you push with a certain speed, what force does that require?” he says. “And that’s actually an age-old problem.”

Push too fast, and you might shatter a glass carafe or see the coffee spew out the top.

In a lab full of fancy science equipment, Wadsworth and colleagues could test this idea using a uniaxial press to apply a constant speed to a carafe full of coffee and water (rather than its normal use to test soil compaction). With the idea that this is the perfect home-brewed science, the team developed the equation. For a press that travels 10 cm over 60 s, for example, the average fluid velocity is 17 mm/s. The researchers calculate that the force is 32 N.

Admittedly, this Newscriptster had not yet had enough coffee to work through the complex math when we talked, but Wadsworth was well into his day and well into his caffeine.

“I have a problem,” Wadsworth says, mentioning that scientists love their coffee. “I’ve had six espressos already. I think now’s the time to stop.”

Barbie, the virus slayer

She’s an icon, a celebrity, and made of multiple kinds of plastic. And now, Barbie is a pandemic hero. As part of the company’s charitable programs, Mattel has bestowed upon six women their likenesses on the most famous doll in the world. The women, the company says in a statement, “have worked tirelessly in the fight against COVID-19.”

Among the six is Sarah Gilbert, a vaccine expert at Oxford University who led the development of what became the Oxford AstraZeneca COVID-19 vaccine. Gilbert, who led Ebola vaccine trials and helped develop Oxford’s malaria vaccine, became a vaccine developer almost by accident, the BBC reports.

This suite of Barbies is multinational. In addition to Gilbert, who is based in the UK, there’s Jaqueline Góes de Jesus, of Brazil, who led the sequencing of a COVID-19 variant found in that country. Kirby White, of Australia, invented a reusable safety gown for frontline workers. And Chika Stacy Oriuwa, of Canada, has fought against racism in health care, which has been exacerbated by COVID-19.

The two US celebrants are Amy O’Sullivan, a nurse who treated the first COVID-19 patient in Brooklyn, became critically ill herself, then recovered and went back to the COVID-19 wards, and Audrey Sue Cruz, an internist who has been fighting discrimination against Asians during the pandemic.

These scientific and medical Barbies add to a growing list of the dolls’ representations of what girls can be. But don’t put one on your holiday wish list. A Mattel spokeswoman tells Newscripts that the dolls are a gift to the women who inspired them and won’t be available commercially.

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