Experiments reveal a potentially useful odd–even dichotomy in the nonlinear Hall response of bilayer graphene.
Get the latest international news and world events from around the world.
Small molecular twists may strengthen nature’s magnetic compass
A collaborative research team led by Yasuhiro Kobori at Kobe University, together with researchers from Toho University, Saitama University, Nagoya Institute of Technology and the University of Freiburg, has identified a potential molecular mechanism that could enhance magnetic compass responses in cryptochrome, a blue-light-sensitive protein implicated in magnetoreception.
Using time-resolved electron paramagnetic resonance (EPR) spectroscopy, the team identified structural rearrangements in light-induced intermediates and a contribution from chirality-induced spin selectivity (CISS). Their analysis suggests that chiral rotational motion of a tryptophan residue can influence electron-spin polarization and enhance the directional dependence of downstream chemical reactions.
Their findings are published in The Journal of Physical Chemistry Letters.
Electrical guardrails for charge carriers: A new approach to harness graphene for solar cells
Graphene is a single layer of carbon atoms in which electrons can move with high mobility, making it promising for high-speed electronic components. Yet it is not very efficient at converting light into electricity. While light absorbed by graphene does excite electrons, leaving behind positively charged carriers called ‘holes,’ the absorbed light energy cannot be harnessed effectively unless electrons and holes are separated and directed to different contacts.
Conventional solar cells use semiconductors such as silicon, whose bandgap plays a key role in converting light into electrical energy. Graphene does not have such a gap.
“That’s why we have to come up with a different mechanism,” says Ralf Schützhold, director of the HZDR Institute of Theoretical Physics. One option is to cut or fold the graphene to create tiny edges.
Evolutionary changes in key enzyme may help bacteria make proteins faster
Evolutionary changes in a key protein synthesis enzyme, isoleucyl-tRNA synthetase (IleRS), may help bacteria fine-tune how quickly proteins are made, report researchers from Institute of Science Tokyo, Japan; the University of Zagreb Faculty of Science, Croatia; and ETH Zürich, Switzerland.
Researchers traced the enzyme’s evolutionary history and identified three distinct IleRS clades. Their findings show that C-terminal remodeling, including repeated loss of a structural region called “INS,” may have helped refine enzyme activity and reaction speed.
The study is published in the journal Nature Communications.
Simplified ancestral enzyme makes ATP without amino acid needed for its usual reaction
Proteins perform essential functions in living organisms, from catalyzing biochemical reactions to supporting cellular energy metabolism. Their functions depend on their amino acid composition and three-dimensional structures. However, early proteins may have evolved when fewer amino acid types were available than those used by most modern proteins.
Understanding how proteins built from a more limited set of amino acids could perform essential biochemical reactions may therefore offer insights into the origins and evolution of life.
Cosmic microwave background offers evidence of gas flowing in galaxy clusters
The cosmic microwave background (CMB) is a faint glow in the universe dating back to roughly 380,000 years after the Big Bang, long before stars or galaxies emerged. Detecting this light and mapping its fluctuations provide valuable insights into the age and composition of the universe.
Researchers at Columbia University recently analyzed CMB data and gathered evidence of a CMB signal that could be produced by internal gas motions in galaxy clusters, large collections of galaxies that are held together by gravity. Their findings, published in Physical Review Letters, strengthen earlier clues of this gas motion and a phenomenon called the rotational kinematic Sunyaev-Zel’dovich (rkSZ) effect reported by other astronomers.
“This project began after a meeting with my Ph.D. adviser, J. Colin Hill, in which we discussed signals in the CMB that hadn’t yet been observed,” Samuel Goldstein, first author of the paper, told Phys.org. “One of these is the rkSZ effect. As CMB photons pass through a galaxy cluster, they scatter off its ionized gas, and if the gas is rotating, one side of the cluster appears slightly hotter and the other slightly colder.”
Asteroids venturing near white dwarfs don’t break directly into dust, study reveals
When asteroids travel too close to white dwarfs, the dense remnants of stars that have exhausted their nuclear fuel, powerful gravitational forces can tear them apart. However, new research from Planetary Science Institute (PSI) suggests that these asteroids don’t immediately break into dust. Instead, most of the mass initially remains in larger fragments, revealing a previously overlooked step in how debris forms around dying stars.
The study, led by PSI senior scientist Jordan Steckloff, identifies a “kilometer-size barrier” that limits just how much asteroids can break apart when subjected to the powerful gravitational forces of white dwarfs.
White dwarfs are often surrounded by disks of planetary debris, including dust from asteroids and other objects pulled apart by the star’s gravity. Previous models have generally assumed that these objects behave like loosely bound piles of rubble with no internal strength. This allows them to break into increasingly smaller pieces and eventually turn into dust.
A hidden brain rhythm challenges ideas about where consciousness comes from
How our brains give rise to consciousness is one of the biggest mysteries in neuroscience. But new research by Janis Hesse at the University of California, Berkeley, and colleagues, may help fill in some of the details. The insights are coming from studies on macaque monkeys.
For years, neuroscientists have been divided over whether the neural mechanisms underlying consciousness lie primarily in the front or the back of the brain. Some researchers champion frontal regions through frameworks like global neuronal workspace and higher-order models. Others support posterior zones through models like integrated information theory and recurrent processing.
This new study suggests both camps might be arguing about the wrong thing.
New catalyst builds proton highways to tackle a long-standing hurdle in green ammonia synthesis
Over a century ago, the Haber-Bosch process, a two-step reaction for the synthesis of ammonia (NH₃), an irreplaceable chemical for the fertilizer industry, prevented the world from going into a serious food crisis. Today, however, the same method consumes about 1% of global energy and contributes more than 1% of annual anthropogenic CO₂ emissions.
In a recent study, researchers designed a new covalent organic framework that provided a promising solution to a long-standing problem in green ammonia synthesis.
The team designed hydroxyl-functionalized copper phthalocyanine-based covalent organic frameworks as electrocatalysts for electrocatalytic nitrate reduction (NO₃RR). This process emerged as a viable, greener alternative to the industrial Haber-Bosch process, which is known to rely heavily on harsh high-temperature and high-pressure conditions.
How the quantum vacuum perturbs atoms, could shrink black holes and may have helped form galaxies
The word “vacuum” may conjure the image of empty space. Maybe you think of a region far outside the solar system without planets, debris, gas clouds or light. According to quantum theory, however, a vacuum is never truly empty. Quantum mechanics extends the Heisenberg uncertainty principle —which states that we cannot measure the position and the velocity of an object exactly at the same time—to a vacuum. The result is that a vacuum can never be still.
Instead of an empty space, we can imagine the vacuum as a dynamic object, with regular fluctuations in energy.
Physicists at the University of Cambridge in the United Kingdom recently presented preliminary research showing direct imaging of these fluctuations in a lab-made quantum vacuum. Physicists have “seen” the quantum vacuum many times before, however. And we can all see the effects of the quantum vacuum on atoms in the atmosphere—through the gorgeous light displays of the aurora borealis.