There are thousands of YouTube videos in which DIY science enthusiasts cut grapes in half—leaving just a thin bit of skin connecting them—and put the grapes in the microwave, just to marvel at the sparks and plume of ionized gas (plasma) that the grapes produce. This quirky property of grapes might help make more efficient quantum sensors, according to a new paper published in the journal Physical Review Applied.

The plasma-inducing grape effect was first observed in 1994, per the authors. As previously reported , the usual explanation for the generation of plasmas is that grapes are so small that the irradiating microwaves become highly concentrated in the grape tissue, ripping some the molecules apart to generate charged ions (adding to the electrolytes already present in the grapes). The electromagnetic field that forms causes ions to flow from one grape half to the other via the connecting skin—at least at first. That's when you get the initial sparks. Eventually, the ions start passing through the surrounding air as well, ionizing it to produce that hot plume of plasma.

But in 2019, Trent University scientists showed that explanation isn't quite right. The skin bridge isn't necessary for the effect to occur. Rather, the plasma is generated by an electromagnetic "hot spot." The grapes have the right refractive index and size to "trap" microwaves, so putting two of them close together leads to the generation of a hot spot between them. The trick also works with gooseberries, large blackberries, and quail eggs, as well as hydrogel beads—plastic beads soaked in water. ("Many microwaves were in fact harmed during the experiments," co-author Hamza Khattak admitted at the time.)

Read full article

Comments

There are thousands of YouTube videos in which DIY science enthusiasts cut grapes in half—leaving just a thin bit of skin connecting them—and put the grapes in the microwave, just to marvel at the sparks and plume of ionized gas (plasma) that the grapes produce. This quirky property of grapes might help make more efficient quantum sensors, according to a new paper published in the journal Physical Review Applied.

The plasma-inducing grape effect was first observed in 1994, per the authors. As previously reported , the usual explanation for the generation of plasmas is that grapes are so small that the irradiating microwaves become highly concentrated in the grape tissue, ripping some the molecules apart to generate charged ions (adding to the electrolytes already present in the grapes). The electromagnetic field that forms causes ions to flow from one grape half to the other via the connecting skin—at least at first. That's when you get the initial sparks. Eventually, the ions start passing through the surrounding air as well, ionizing it to produce that hot plume of plasma.

But in 2019, Trent University scientists showed that explanation isn't quite right. The skin bridge isn't necessary for the effect to occur. Rather, the plasma is generated by an electromagnetic "hot spot." The grapes have the right refractive index and size to "trap" microwaves, so putting two of them close together leads to the generation of a hot spot between them. The trick also works with gooseberries, large blackberries, and quail eggs, as well as hydrogel beads—plastic beads soaked in water. ("Many microwaves were in fact harmed during the experiments," co-author Hamza Khattak admitted at the time.)

Read full article

Comments

There are thousands of YouTube videos in which DIY science enthusiasts cut grapes in half—leaving just a thin bit of skin connecting them—and put the grapes in the microwave, just to marvel at the sparks and plume of ionized gas (plasma) that the grapes produce. This quirky property of grapes might help make more efficient quantum sensors, according to a new paper published in the journal Physical Review Applied.

The plasma-inducing grape effect was first observed in 1994, per the authors. As previously reported , the usual explanation for the generation of plasmas is that grapes are so small that the irradiating microwaves become highly concentrated in the grape tissue, ripping some the molecules apart to generate charged ions (adding to the electrolytes already present in the grapes). The electromagnetic field that forms causes ions to flow from one grape half to the other via the connecting skin—at least at first. That's when you get the initial sparks. Eventually, the ions start passing through the surrounding air as well, ionizing it to produce that hot plume of plasma.

But in 2019, Trent University scientists showed that explanation isn't quite right. The skin bridge isn't necessary for the effect to occur. Rather, the plasma is generated by an electromagnetic "hot spot." The grapes have the right refractive index and size to "trap" microwaves, so putting two of them close together leads to the generation of a hot spot between them. The trick also works with gooseberries, large blackberries, and quail eggs, as well as hydrogel beads—plastic beads soaked in water. ("Many microwaves were in fact harmed during the experiments," co-author Hamza Khattak admitted at the time.)

Read full article

Comments

The Federal Trade Commission is investigating Microsoft in a wide-ranging probe that will examine whether the company’s business practices have run afoul of antitrust laws, according to people familiar with the matter. In recent weeks, FTC attorneys have been conducting interviews and setting up meetings with Microsoft competitors.

One key area of interest is how the world’s largest software provider packages popular Office products together with cybersecurity and cloud computing services, said one of the people, who asked not to be named discussing a confidential matter.

This so-called bundling was the subject of a recent ProPublica investigation , which detailed how, beginning in 2021, Microsoft used the practice to vastly expand its business with the US government while boxing competitors out of lucrative federal contracts.

Read full article

Comments

The Federal Trade Commission is investigating Microsoft in a wide-ranging probe that will examine whether the company’s business practices have run afoul of antitrust laws, according to people familiar with the matter. In recent weeks, FTC attorneys have been conducting interviews and setting up meetings with Microsoft competitors.

One key area of interest is how the world’s largest software provider packages popular Office products together with cybersecurity and cloud computing services, said one of the people, who asked not to be named discussing a confidential matter.

This so-called bundling was the subject of a recent ProPublica investigation , which detailed how, beginning in 2021, Microsoft used the practice to vastly expand its business with the US government while boxing competitors out of lucrative federal contracts.

Read full article

Comments

The Federal Trade Commission is investigating Microsoft in a wide-ranging probe that will examine whether the company’s business practices have run afoul of antitrust laws, according to people familiar with the matter. In recent weeks, FTC attorneys have been conducting interviews and setting up meetings with Microsoft competitors.

One key area of interest is how the world’s largest software provider packages popular Office products together with cybersecurity and cloud computing services, said one of the people, who asked not to be named discussing a confidential matter.

This so-called bundling was the subject of a recent ProPublica investigation , which detailed how, beginning in 2021, Microsoft used the practice to vastly expand its business with the US government while boxing competitors out of lucrative federal contracts.

Read full article

Comments

When you want to move an object from one place to another, you usually grab it with your hands or a robotic arm. But what if you want to move something you cannot touch without damaging or disrupting it, like a droplet of liquid? A solution proposed by a team of scientists at the North Carolina State University is a metamaterial that can change shape in response to magnetic fields.

This material had to be easily deformable to change shape, yet at the same time stiff enough to bear loads. “That seemed contradictory—how do you make something that is stiff and deformable at once?” says Jie Yin, a mechanical metamaterials researcher at NC State. His team did it with ferromagnetic elastomers, kirigami cuts, balloons, and magnets.

Refreshable Braille display

“There is not much research on using magnets to manipulate non-magnetic objects. It is very, very hard,” says Yinding Chi, another NC State researcher and lead author of the study. The idea Chi and his colleagues came up with could be compared to a refreshable Braille display . They imagined a surface dotted with domes that could rise, turn, or depress on demand, allowing it to dynamically form relief-like images or move in a pattern similar to waves in the ocean. Objects would then move on these surfaces like they were carried by waves. “This way, you can move various objects without using grippers,” Yin says.

Read full article

Comments

When you want to move an object from one place to another, you usually grab it with your hands or a robotic arm. But what if you want to move something you cannot touch without damaging or disrupting it, like a droplet of liquid? A solution proposed by a team of scientists at the North Carolina State University is a metamaterial that can change shape in response to magnetic fields.

This material had to be easily deformable to change shape, yet at the same time stiff enough to bear loads. “That seemed contradictory—how do you make something that is stiff and deformable at once?” says Jie Yin, a mechanical metamaterials researcher at NC State. His team did it with ferromagnetic elastomers, kirigami cuts, balloons, and magnets.

Refreshable Braille display

“There is not much research on using magnets to manipulate non-magnetic objects. It is very, very hard,” says Yinding Chi, another NC State researcher and lead author of the study. The idea Chi and his colleagues came up with could be compared to a refreshable Braille display . They imagined a surface dotted with domes that could rise, turn, or depress on demand, allowing it to dynamically form relief-like images or move in a pattern similar to waves in the ocean. Objects would then move on these surfaces like they were carried by waves. “This way, you can move various objects without using grippers,” Yin says.

Read full article

Comments

When you want to move an object from one place to another, you usually grab it with your hands or a robotic arm. But what if you want to move something you cannot touch without damaging or disrupting it, like a droplet of liquid? A solution proposed by a team of scientists at the North Carolina State University is a metamaterial that can change shape in response to magnetic fields.

This material had to be easily deformable to change shape, yet at the same time stiff enough to bear loads. “That seemed contradictory—how do you make something that is stiff and deformable at once?” says Jie Yin, a mechanical metamaterials researcher at NC State. His team did it with ferromagnetic elastomers, kirigami cuts, balloons, and magnets.

Refreshable Braille display

“There is not much research on using magnets to manipulate non-magnetic objects. It is very, very hard,” says Yinding Chi, another NC State researcher and lead author of the study. The idea Chi and his colleagues came up with could be compared to a refreshable Braille display . They imagined a surface dotted with domes that could rise, turn, or depress on demand, allowing it to dynamically form relief-like images or move in a pattern similar to waves in the ocean. Objects would then move on these surfaces like they were carried by waves. “This way, you can move various objects without using grippers,” Yin says.

Read full article

Comments