A team of researchers from the University of Washington has found evidence that the Earth’s atmosphere approximately 2.7 billion years ago might have been up to 70 percent carbon dioxide. In their paper published in the journal Science Advances, the group describes their study of micrometeorites and what they learned from them.

As scientists continue to study Earth’s past, they look for evidence of what environmental conditions might have been like in hopes of understanding how life arose. One important piece of the puzzle is the atmosphere. Scientists suspect that its ingredients were far different billions of years ago, but they have little in the way of evidence to prove it. In this new endeavor, the researchers looked to micrometeorites as a possible source of clues. Their thinking was that any material from space that made its way to the surface of the planet had to travel first through the atmosphere—and any material that travels through the atmosphere is highly influenced by its materials, largely due to the high temperatures of atmospheric entry.

Several years ago, researchers found a host of micrometeorites that had landed on Earth approximately 2.7 billion years ago, putting them squarely in the Archean Eon—the time during which it is believed life first appeared on Earth. Study of the micrometeorites showed that they contained high levels of iron along with wüstite. Wüstite forms when iron is exposed to oxygen, but not on the Earth’s surface. It must have been created as the grain-sized meteorites burned and fell through the Earth’s atmosphere. Intrigued by the finding, the researchers created a computer model to simulate the conditions that would lead to the creation of materials such as wüstite on a rock falling through the atmosphere.

Styrofoam or copper—both materials have very different properties with regard to their ability to conduct heat. Scientists at the Max Planck Institute for Polymer Research (MPI-P) in Mainz and the University of Bayreuth have now jointly developed and characterized a novel, extremely thin and transparent material that has different thermal conduction properties depending on the direction. While it can conduct heat extremely well in one direction, it shows good thermal insulation in the other direction.

Thermal insulation and thermal conduction play a crucial role in our everyday lives—from computer processors, where it is important to dissipate heat as quickly as possible, to houses, where good insulation is essential for energy costs. Often extremely light, porous materials such as polystyrene are used for insulation, while heavy materials such as metals are used for heat dissipation. A newly developed material, which scientists at the MPI-P have jointly developed and characterized with the University of Bayreuth, can now combine both properties.

The material consists of alternating layers of wafer-thin glass plates between which individual polymer chains are inserted. “In principle, our material produced in this way corresponds to the principle of double glazing,” says Markus Retsch, Professor at the University of Bayreuth. “It only shows the difference that we not only have two layers, but hundreds.”

Use of an AC rather than a DC electric field can improve the piezoelectric response of a crystal. Now, an international team of researchers say that cycles of AC fields also make the internal crystal domains in some materials bigger and the crystal transparent.

“There have been reports that the use of AC fields could significantly improve the piezoelectric responses—for example by 20% to 40%—over DC fields and the improvements have always been attributed to the smaller internal ferroelectric domain sizes that resulted from the cycles of AC fields,” said Long-Qing Chen, Hamer Professor of Materials Science and Engineering, professor of engineering science and mechanics, and professor of mathematics at Penn State. “About three years ago, Dr. Fei Li, then a research associate at the Materials Research Institute at Penn State, largely confirmed the improvement of piezoelectric performances from application of AC fields. However, it was not clear at all how the internal ferroelectric domains evolved during AC cycles.

”Our group does mostly computer modeling, and more than a year ago we started looking into what happens to the internal domain structures if we apply AC fields to a ferroelectric piezoelectric crystal. We are very curious about how the domain structures evolve during AC cycles. Our computer simulations and theoretical calculations did show an improved piezoelectric response, but our simulations also demonstrated that the ferroelectric domain sizes actually got bigger during AC cycles rather than smaller as reported in the literature.”