A team of physicists has created a new way to self-assemble particles—an advance that offers new promise for building complex and innovative materials at the microscopic level.
Self-assembly, introduced in the early 2000s, gives scientists a means to “pre-program” particles, allowing for the building of materials without further human intervention—the microscopic equivalent of Ikea furniture that can assemble itself.
The breakthrough, reported in the journal Nature, centers on emulsions—droplets of oil immersed in water—and their use in the self-assembly of foldamers, which are unique shapes that can be theoretically predicted from the sequence of droplet interactions.
Have you ever been faced with a problem where you had to find an optimal solution out of many possible options, such as finding the quickest route to a certain place, considering both distance and traffic?
If so, the problem you were dealing with is what is formally known as a “combinatorial optimization problem.” While mathematically formulated, these problems are common in the real world and spring up across several fields, including logistics, network routing, machine learning, and materials science.
However, large-scale combinatorial optimization problems are very computationally intensive to solve using standard computers, making researchers turn to other approaches. One such approach is based on the “Ising model,” which mathematically represents the magnetic orientation of atoms, or “spins,” in a ferromagnetic material.
Researchers at UCLA have created an edible particle that helps make lab-grown meat, known as cultured meat, with more natural muscle-like texture using a process that could be scaled up for mass production.
Led by Amy Rowat, who holds UCLA’s Marcie H. Rothman Presidential Chair of Food Studies, the researchers have invented edible particles called microcarriers with customized structures and textures that help precursor muscle cells grow quickly and form muscle-like tissues. Edible microcarriers could reduce the expense, time, and waste required to produce cultured meat with a texture that appeals to consumers. The results are published in the journal Biomaterials.
“Animal cells that can be coaxed to form tissues similar to meats could offer a protein source to a world facing food insecurity caused by threats ranging from epidemics to natural disasters,” said Rowat, who is an associate professor of integrative biology and physiology at the UCLA College. “Cultured meat products are not yet on the market in the U.S. and strategies to enable mass production are still emerging.”
Jülich researchers have been able to demonstrate an exotic electronic state, so-called Fermi Arcs, for the first time in a 2D material. The surprising appearance of Fermi arcs in such a material provides a link between novel quantum materials and their respective potential applications in a new generation of spintronics and quantum computing. The results have recently been published in Nature Communications.
The newly detected Fermi arcs represent special—arc-like—deviations from the so-called Fermi surface. The Fermi surface is used in condensed matter physics to describe the momentum distribution of electrons in a metal. Normally, these Fermi surfaces represent closed surfaces. Exceptions such as the Fermi arcs are very rare and often are associated with exotic properties like superconductivity, negative magnetoresistance and anomalous quantum transport effects.
Today’s technology challenge is to develop the “on-demand” control of physical properties in materials. However, such experimental tests have been largely limited to bulk materials and are key grand challenges in condensed matter science. With its groundbreaking paradigm, the findings present a promising new frontier for quantum control of topological states in low-dimensional systems by external means—the external magnetic field that offers unprecedented capabilities on 2D materials for artificial intelligence as well as future information processing.
Theorists at the University of Pittsburgh and Swansea University have shown that recent experimental results from the CERN collider give strong evidence for a new form of matter.
The experiment at CERN, site of the world’s highest-energy particle collider, examined a heavy particle called a Lambda b that decays to lighter particles, including the familiar proton and the famed J/psi, discovered in 1974.
In a paper published online today in Physical Review D, physicists Tim Burns of Swansea in Wales and Eric Swanson at Pitt argue that the data can be understood only if a new type of matter exists.
Physicists at UC Santa Barbara, the University of Maryland, and the University of Washington have found an answer to the longstanding physics question: How do interparticle interactions affect dynamical localization?
“It’s a really old question inherited from condensed matter physics,” said David Weld, an experimental physicist at UCSB with specialties in ultracold atomic physics and quantum simulation. The question falls into the category of “many-body” physics, which interrogates the physical properties of a quantum system with multiple interacting parts. While many-body problems have been a matter of research and debate for decades, the complexity of these systems, with quantum behaviors such as superposition and entanglement, lead to multitudes of possibilities, making it impossible to solve through calculation alone. “Many aspects of the problem are beyond the reach of modern computers,” Weld added.
Fortunately, this problem was not beyond the reach of an experiment that involves ultracold lithium atoms and lasers. So, what emerges when you introduce interaction in a disordered, chaotic quantum system? A “weird quantum state,” according to Weld. “It’s a state which is anomalous, with properties which in some sense lie between the classical prediction and the non-interacting quantum prediction.”
In molecules, the atoms vibrate with characteristic patterns and frequencies. Vibrations are therefore an important tool for studying molecules and molecular processes such as chemical reactions. Although scanning tunneling microscopes can be used to image individual molecules, their vibrations have so far been difficult to detect.
Physicists at Kiel University (Christian-Albrechts-Universität zu Kiel, CAU) have now invented a method with which the vibration signals can be amplified by up to a factor of 50. Furthermore, they increased the frequency resolution considerably. The new method will improve the understanding of interactions in molecular systems and further simulation methods. The research team has now published the results in the journal Physical Review Letters.
The discovery by Dr. Jan Homberg, Dr. Alexander Weismann and Prof. Dr. Richard Berndt from the Institute of Experimental and Applied Physics, relies on a special quantum mechanical effect, so-called “inelastic tunneling”. Electrons that pass through a molecule on their way from a metal tip to the substrate surface in the scanning tunneling microscope can release energy to the molecule or take energy up from it. This energy exchange occurs in portions determined by the properties of the respective molecule.
Neutronium was the material used in the hull of the doomsday machine in Star Trek.
Now I’m not terribly sure what the mechanical properties of neutronium would be like. It certainly is very dense (about a billion tons per cm3, about the volume of the end of your little finger), but it interacts with matter only weakly. I would expect both it to be pretty inefficient at stopping both electromagnetic radiation (neutrons only have a magnetic moment), and matter.
However in reality there’s a somewhat bigger problem. When neutrons are outside of the nucleus of atoms, or are outside the huge pressure that exists in neutron stars, they have a half life of about 10 minutes. To make it even more awkward, when a neutron decays, it releases about a MeV of energy. So put a few extra numbers into this, like a mole of neutrons (6e23 neutrons) weighs about a gram, and a ton of TNT is 4e9 Joules and you can work out that just the neutrons in your typical human (about half your body weight), will release about the same energy as a megaton (one million tons of TNT). A little more scratching around on half life calculations and you can work out that if you have a half life of 10 minutes, then you will release about 1 part in 1,000 of its total energy in the very first second.
This means that if you could extra merely a ml of neutronium, and free it from that immense pressure, then it would release the same energy as 15 million Czar bombs (the largest man-made bomb ever) in the very first second.
Imagine a world where super-strong, super-light, flexible, durable new materials, which don’t exist in nature could be made to order. New breakthroughs in the understanding of “spin”, a characteristic of subatomic particles — like mass and charge — mean we are on the brink of such a revolution.
“The ability to control spin, one of the fundamental properties of particles, is crucial to us being able to design advanced new materials that will change the world,” says Prof Alessandro Lunghi, a physicist at Trinity College Dublin, who heads up a team investigating the phenomenon.
The scientific concepts of particle mass and charge are widely understood and known, but the third property of particles — that of spin — remains mysterious to most. It’s a concept that even many scientists struggle to understand.
