Up to a certain point, very luminous stars can have a positive effect on the formation of planets, but from that point on the radiation they emit can cause the material in protoplanetary discs to disperse.
Category: materials – Page 95
Space elevators are inching closer to reality
https://www.freethink.com/space/space-elevator đž: VectorMine / Adobe Stock
The researchers are still working on the issue of scaling up production, but in 2021, state-owned news outlet Xinhua released a video depicting an in-development concept, called âSky Ladder,â that would consist of space elevators above Earth and the moon.
After riding up the Earth-based space elevator, a capsule would fly to a space station attached to the tether of the moon-based one. If the project could be pulled off â a huge if â China predicts Sky Ladder could cut the cost of sending people and goods to the moon by 96%.
In the 120 years since Tsiolkovsky looked at the Eiffel Tower and thought way bigger, tremendous progress has been made developing materials with the properties needed for a space elevator. At this point, it seems likely we could one day have a material that can be manufactured at the scale needed for a tether â but by the time that happens, the need for a space elevator may have evaporated.
Ultra-flat optics for broadband thermal imaging
Long-wavelength infrared (LWIR) imaging holds critical significance across many applications, from consumer electronics to defense and national security. It finds applications in night vision, remote sensing, and long-range imaging. However, the conventional refractive lenses employed in these imaging systems are bulky and heavy, which is undesirable for almost all applications. Compounding this issue is the fact that many LWIR refractive lenses are crafted from expensive and limited-supply materials, such as germanium.
Photon-like electrons in a four-dimensional world discovered in a real material
Because of their differences from standard electrons, Dirac electrons are expected to add unprecedented electronic properties to materials. For example, they could be applied to electronic devices to perform computation and communication with extraordinary efficiency and low energy consumption.
To develop such technology, scientists must first understand the net properties and effects of Dirac electrons. But they generally coexist with standard electrons in materials, which prevents unambiguous observation and measurement.
In a recent study published in Materials Advances, Ryuhei Naito and colleagues discovered a method enabling selective observation of the Dirac electrons in materials. Using electron spin resonance, to directly observe unpaired electrons in materials to distinguish differences in character, the research group established a method to determine their scope of action in the materials and their energies.
Researchers prove fundamental limits of electromagnetic energy absorption
Electrical engineers at Duke University have determined the theoretical fundamental limit for how much electromagnetic energy a transparent material with a given thickness can absorb. The finding will help engineers optimize devices designed to block certain frequencies of radiation while allowing others to pass through, for applications such as stealth or wireless communications.
How to upcycle low-energy light: A new design for highly efficient conversion materials
To combine two low-energy photons into one high-energy photon efficiently, the energy must be able to hop freely, but not too quickly, between randomly oriented molecules of a solid. This Kobe University discovery provides a much-needed design guideline for developing materials for more efficient PV cells, displays, or even anti-cancer therapies.
Light of different colors has different energies and is therefore useful for very different things. For the development of more efficient PV cells, OLED displays, or anti-cancer therapies, it is desirable to be able to upcycle two low-energy photons into a high-energy photon, and many researchers worldwide are working on materials for this up-conversion.
During this process, light is absorbed by the material, and its energy is handed around among the materialâs molecules as a so-called âtriplet exciton.â However, it was unclear what allows two triplet excitons to efficiently combine their energies into a different excited state of a single molecule that then emits a high-energy photon, and this knowledge gap has been a serious bottleneck in the development of such materials.
Giant âsand batteryâ holds a weekâs heat for a whole town
A new industrial-scale âsand batteryâ has been announced for Finland, which packs 1 MW of power and a capacity of up to 100 MWh of thermal energy for use during those cold polar winters. The new battery will be about 10 times bigger than a pilot plant thatâs been running since 2022.
The sand battery, developed by Polar Night Energy, is a clever concept. Basically, itâs a big steel silo of sand (or a similar solid material) thatâs warmed up through a heat exchanger buried in the center, using excess electricity from the grid â say, that generated during a spike from renewable sources, when itâs cheap.
That energy can then be stored for months at a time, with reportedly very little loss, before being extracted as heat on demand. This could theoretically be converted back into electricity, although with some energy loss. But Polar Night says that the most efficient method is to just use the heat itself.
Seismological study shows ancient lower mantle flow field under Philippine sea plate
Researchers from China and Japan have discovered distinct characteristics of Earthâs lower mantle flow field. They investigated seismic anisotropy in the upper part of the lower mantle beneath the Philippine Sea Plate (PSP) and found that the ancient lower mantle flow field is still preserved there.
The study is published in Nature Geoscience.
The lower mantle is an important layer of the Earth and may play an important role in the evolution and material cycling of Earthâs interior. It is generally believed to be not only the final destination of subducted slabs, but also the birthplace of mantle plumes, which are two major styles in the evolution and material cycling of the Earthâs surface and interior. However, our knowledge of the characteristics of the flow field and geodynamics of the lower mantle is still deficient.
A rare nova ignites a ânew starâ in the sky this year. Hereâs how to see it
A nova outburst visible to the naked eye is expected to decorate the night sky this year, offering a rare skywatching opportunity.
The star system offering us this opportunity is known as T Coronae Borealis (T CrB). Itâs located some 3,000 light-years away from Earth and consists of a red giant star and a white dwarf that orbit each other. When the white dwarf steals enough stellar material from its red giant companion, it ignites a brief flash of nuclear fusion on its surface, triggering what is known as a nova outburst.