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In the periodic table of elements there is one golden rule for carbon, oxygen and other light elements: Under high pressures, they have similar structures to heavier elements in the same group of elements. But nitrogen always seemed unwilling to toe the line. However, high-pressure chemistry researchers of the University of Bayreuth have disproved this special status. Out of nitrogen, they created a crystalline structure which, under normal conditions, occurs in black phosphorus and arsenic. The structure contains two-dimensional atomic layers, and is therefore of great interest for high-tech electronics. The scientists have presented this “black nitrogen” in Physical Review Letters.

Nitrogen—an exception in the periodic system?

When you arrange the chemical elements in ascending order according to their number of protons and look at their properties, it soon becomes obvious that certain properties recur at large intervals (periods). The periodic table of elements brings these repetitions into focus. Elements with similar properties are placed one below the other in the same column, and thus form a group of elements. At the top of a column is the element that has the fewest protons and the lowest weight compared to the other group members. Nitrogen heads element group 15, but was previously considered the “black sheep” of the group. The reason: In earlier high-pressure experiments, nitrogen showed no structures similar to those exhibited under normal conditions by the heavier elements of this group—specifically, phosphorus, arsenic and antimony. Instead, such similarities are observed at high pressures in the neighboring groups headed by carbon and oxygen.

Pressure puts a new twist on magic-angle bilayers.

An international team of researchers has discovered the hydrogen atoms in a metal hydride material are much more tightly spaced than had been predicted for decades — a feature that could possibly facilitate superconductivity at or near room temperature and pressure.

Such a superconducting material, carrying electricity without any energy loss due to resistance, would revolutionize energy efficiency in a broad range of consumer and industrial applications.

The scientists conducted neutron scattering experiments at the Department of Energy’s Oak Ridge National Laboratory on samples of zirconium vanadium hydride at atmospheric pressure and at temperatures from −450 degrees Fahrenheit (5 K) to as high as −10 degrees Fahrenheit (250 K) — much higher than the temperatures where superconductivity is expected to occur in these conditions.

Process is cheap and more environmentally friendly, say researchers.

Research of landmine detection using terahertz technology.

Scientific. Net, the trademark of Trans Tech Publications Ltd., is one of the largest web resources, publishes peer-reviewed academic journals and book series in field of materials science and engineering.

Materials scientists aim to engineer intelligence into the fabric of materials or metamaterials for programmable functions. Engineering efforts can vary from passive to active forms to develop programmable metasurfaces using dynamic and arbitrary electromagnetic (EM) wavefields. Such metasurfaces, however, require manual control to switch between functions. In a new study now published on Light: Science & Applications, Qian Ma and an interdisciplinary research team in the State Key Laboratory, Cyberspace Science and Technology, and the Department of Electronics in China engineered a smart metasurface for self-adaptive programmability.

Circa 2016

Not all important scientific research is cool looking, or has a cool name. But now and then you get something with both. These self-assembling carbon nanotubes are created with a process called Teslaphoresis. If you’ve read a more impressive-sounding sentence today, I’d like to hear it.

Even the lab of Rice University chemist Paul Cherukuri looks like a proper mad scientist’s lair. But don’t let the flashy trappings fool you: this is a very significant development.

Continue reading “Teslaphoresis-activated self-assembling carbon nanotubes look even cooler than they sound” »

Researchers have designed a new way to make concrete that would make frustrating cracks a thing of the past.

We report terahertz (THz) light-induced second harmonic generation, in superconductors with inversion symmetry that forbid even-order nonlinearities. The THz second harmonic emission vanishes above the superconductor critical temperature and arises from precession of twisted Anderson pseudospins at a multicycle, THz driving frequency that is not allowed by equilibrium symmetry. We explain the microscopic physics by a dynamical symmetry breaking principle at sub-THz-cycle by using quantum kinetic modeling of the interplay between strong THz-lightwave nonlinearity and pulse propagation. The resulting nonzero integrated pulse area inside the superconductor leads to light-induced nonlinear supercurrents due to subcycle Cooper pair acceleration, in contrast to dc-biased superconductors, which can be controlled by the band structure and THz driving field below the superconducting gap.