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Scientists at the National University of Singapore (NUS) have introduced a groundbreaking concept known as “supercritical coupling,” which significantly boosts the efficiency of photon upconversion. This innovation not only overturns existing paradigms but also opens a new direction in the control of light emission.

Photon upconversion, the process of converting low-energy photons into higher-energy ones, is a crucial technique with broad applications, ranging from super-resolution imaging to advanced photonic devices. Despite considerable progress, the quest for efficient photon upconversion has faced challenges due to inherent limitations in the irradiance of lanthanide-doped nanoparticles and the critical coupling conditions of optical resonances.

The concept of “supercritical coupling” plays a pivotal role in addressing these challenges. This fundamentally new approach, proposed by a research team led by Professor LIU Xiaogang from the NUS Department of Chemistry and his collaborator, Dr Gianluigi ZITO from the National Research Council of Italy, leverages on the physics of “bound states in the continuum” (BICs). BICs are phenomena that enable light to be trapped in open structures with theoretically infinite lifetimes, surpassing the limits of critical coupling. These phenomena are different from the usual behavior of light.

The first full-size prototype of Manta Ray, an advanced uncrewed underwater vehicle (UUV) produced by the Defense Advanced Research Projects Agency (DARPA), has been revealed in new photos.

The images were released on Monday by Northrup Grumman, one of two prime contractors DARPA selected in late 2021 to produce unique full-scale demonstration vehicles for the program.

Continue reading “Look: New Images Unveil DARPA’s ‘Manta Ray’ Extra-Large Glider for Non-Crewed Undersea Missions” »

Whenever and wherever stars are born, which occurs whenever clouds of gas sufficiently collapse under their own gravity, they come in a wide variety of sizes, colors, temperatures, and masses. The largest, bluest, most massive stars contain the greatest amounts of nuclear fuel, but perhaps paradoxically, those stars are actually the shortest lived. The reason is straightforward: in any star’s core, where nuclear fusion occurs, it only occurs wherever temperatures exceed 4 million K, and the higher the temperature, the greater the rate of fusion.

So the most massive stars might have the most fuel available at the start, but that means they shine brightly as they burn through their fuel quickly. In particular, the hottest regions in the core will exhaust their fuel the fastest, leading the most massive stars to die the most quickly. The best method we have for measuring “How old is a collection of stars?” is to examine globular clusters, which form stars in isolation often all at once, and then never again. By looking at the cooler, fainter stars that remain (and the lack of hotter, bluer, brighter, more massive stars), we can state with confidence that the Universe must be at least ~12.5–13.0 billion years old.

On Friday 5 April, at 6.25 p.m., the LHC Engineer-in-Charge at the CERN Control Centre (CCC) announced that stable beams were back in the Large Hadron Collider, marking the official start of the 2024 physics data-taking season. The third year of LHC Run 3 promises six months of 13.6 TeV proton collisions at an even higher luminosity than before, meaning more collisions for the experiments to take data from. This will be followed by a period of lead ion collisions in October.

Before the LHC could restart, each accelerator in the CERN complex had to be prepared for another year of physics data taking. Beginning with Linac4, which welcomed its first beam two months ago, each accelerator has gone through a phase of beam commissioning in which it is gradually set up and optimised to be able to control all aspects of the beam, from its energy and intensity to its size and stability. During this phase researchers also test the accelerator’s performance and address any issues before it is used for physics. Following Linac4, which contains the source of protons for the beam, each accelerator was commissioned in turn: the Proton Synchrotron Booster, the Proton Synchrotron, the Super Proton Synchrotron, and finally the LHC from 8 March until 5 April. The whole complex is now ready for data taking.

Back to the CCC. While stable beams are the goal, the CCC engineers must first take several steps to achieve them. First, they must inject the beams into the LHC from the previous accelerators in the chain. Then begins the ramp-up process, which involves increasing the beam energy up to the nominal energy of 6.8 TeV. The next step – shown as “flat top” on LHC Page 1 – is where the energy in the beams is consistent, but they’re not quite ready yet. In order to achieve stable beams, the circulating beams must then be “squeezed” and adjusted using the LHC magnets. This involves making the beams narrower and more centred on their paths, and therefore more likely to produce a high number of collisions in the detectors. Only after the squeezing and adjustment has been completed can stable beams be declared and the experiments around the LHC begin their data taking.

A solid-state battery developer in China has unveiled a new cell that could help change the game for electric mobility. Tailan New Energy’s vehicle-grade all-solid-state lithium batteries offer energy density twice that of other cells in the segment, empowering the Chinese battery maker to hail the cells as a record-setter in the industry.

Tailan New Energy, aka Talent New Energy, is a private solid-state battery developer founded in Beijing, China, in 2018, where it remains headquartered in its research.

Per its website, it was “co-founded by lithium battery R&D experts and a senior domestic industrialization team, focusing on the technological development and industrialization of new solid-state lithium batteries and key lithium battery materials.”

The upcoming entry-level Mercedes-Benz EV dubbed the “one-liter car” for its long-range capabilities, was finally caught out in the wild. In a new video, the electric Mercedes CLA was spotted testing near the Arctic Circle. The new EV is Mercedes-Benz’s answer to the Tesla Model 3.

Mercedes unveiled the electric CLA Concept in September, the first model in a new series of entry-level EVs.

Continue reading “Mercedes-Benz’s sleek new entry-level CLA EV spotted as a Tesla Model 3 rival [Video]” »

Graphene is the setting for the first demonstration of relativistic electrons’ paradoxical ability to whiz through a barrier, provided the barrier is high enough.

If an electron in a material has a speed that is independent of its energy and if it encounters a barrier head on, it can tunnel straight through. Derived by theorist Oskar Klein in 1929, this counterintuitive finding remained little tested in the lab because it is hard to make electrons approach a barrier head on and to stop them scattering off the edges of the sample. Now Mirza Elahi of the University of Virginia and his collaborators have observed evidence of Klein tunneling in monolayer graphene. What’s more, they also observed the opposite effect, anti-Klein tunneling, in bilayer graphene. In anti-Klein tunneling, head-on electrons do not tunnel at all, while others approaching the barrier at an intermediate angle do [1].

Graphene’s hexagonal lattice can be thought of as two identical interpenetrating triangular sublattices. One consequence of that view is that graphene’s charge carriers—electrons that hop between the two sublattices—behave as if massless and relativistic at low energies. Another consequence is that the two sublattices bestow on the electrons a chiral property, pseudospin, that resembles spin, which controls the nature of the transmission across the barrier.

The performance of numerous cutting-edge technologies, from lithium-ion batteries to the next wave of superconductors, hinges on a physical characteristic called intercalation. Predicting which intercalated materials will be stable poses a significant challenge, leading to extensive trial-and-error experimentation in the development of new products.

Now, in a study recently published in ACS Physical Chemistry Au, researchers from the Institute of Industrial Science, The University of Tokyo, and collaborating partners have devised a straightforward equation that correctly predicts the stability of intercalated materials. The systematic design guidelines enabled by this work will speed up the development of upcoming high-performance electronics and energy-storage devices.

The Southwest Research Institute (SwRI) is developing a spacecraft named Astroscale Prototype Servicer for Refueling (APS-R) as part of a $25.5 million project with the U.S. Space Force.

Southwest Research Institute (SwRI) will build, integrate, and test a small demonstration spacecraft as part of a $25.5 million Space Mobility and Logistics (SML) prototyping project funded by the U.S. Space Force and led by prime contractor Astroscale U.S. The spacecraft, called the Astroscale Prototype Servicer for Refueling (APS-R), will refuel other compatible vehicles while in geostationary orbit.

“Running low on fuel is a common issue for spacecraft in Earth orbit,” said SwRI Staff Engineer Steve Thompson, the SwRI project systems engineer. “When they have expended all of their fuel, their mission ends — even though the vehicle may be in otherwise excellent health. A refueling vehicle can extend those missions, and we can get additional lifetime out of spacecraft that are already in orbit.”