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Category: particle physics – Page 659

An elastomer that behaves like an artificial muscle

(Phys.org)—Animal muscle needs to be strong enough to endure strain; it must also be flexible and elastic; and it is self-healing. Finding a polymer that has all of these properties has proved challenging. However, researchers from Stanford, Nanjing University, UC Riverside, Harvard, and the University of Colorado have reported the synthesis of an elastomer that mimics the properties of animal muscle. Their polymer, is also stable at room temperature and not sensitive to water. Their work appears in Nature Chemistry.

Efforts to create polymers that mimic the properties of biological muscle have come short of being practically useful. Often the bonding involved in making these polymers must be sufficiently strong to serve as actuators, but weak enough for reversible self-healing. Many models, to date, involve hydrogen bonding, but are sensitive to water. Li, et al. have, instead, exploited metal-ligand interactions as a way to mimic muscle properties.

The ligand 2,6-pyridinedicarboxamide (pdca)binds to Fe(III) via the pyridyl nitrogen and the nitrogen and oxygen on the carboxamides. Two pdca molecules coordinate to one Fe(III) atom through six coordination sites. Two of the sites are strong bonds (the pyridyl), two sites are “medium” strength bonds (the amides), and two are weak bonds (the carboxyl). Calculations of bond strength show that the strong bonds are similar to covalent bonds, while the weak Fe-O bonds are similar to hydrogen bonding. This multi-bonding structure, as it turns out, provides an excellent framework for making an elastomer.

Iridium Oxide Nanoparticles Used to Harvest Hydrogen

Researchers from Argonne National Laboratory developed a first-principles-based, variable-charge force field that has shown to accurately predict bulk and nanoscale structural and thermodynamic properties of IrO2. Catalytic properties pertaining to the oxygen reduction reaction, which drives water-splitting for the production of hydrogen fuel, were found to depend on the coordination and charge transfer at the IrO2 nanocluster surface. Image: Courtesy of Maria Chan, Argonne National Laboratory

Iridium oxide (IrO2) nanoparticles are useful electrocatalysts for splitting water into oxygen and hydrogen — a clean source of hydrogen for fuel and power. However, its high cost demands that researchers find the most efficient structure for IrO2 nanoparticles for hydrogen production.

A study conducted by a team of researchers at the U.S. Department of Energy’s (DOE’s) Argonne National Laboratory, published in Journal of Materials Chemistry A, describes a new empirical interatomic potential that models the IrO2 properties important to catalytic activity at scales relevant to technology development. Also known as a force field, the interatomic potential is a set of values describing the relationship between structure and energy in a system based on its configuration in space. The team developed their new force field based on the MS-Q force field.

“Before, it was not possible to optimize the shape and size of a particle, but this tool enables us to do this,” says Maria Chan, assistant scientist at Argonne’s Center for Nanoscale Materials (CNM), a DOE Office of Science User Facility.

Quantum logical operations realized with single photons

More insights around the logical quantum gate for photons discovered by Max Planck Institute of Quantum Optics (MPQ). Being able to leverage this gate enables Qubits in transmission and processing can be more controlled and manipulated through this discovery, and places us closer to a stable Quantum Computing environment.

MPQ scientists take an important step towards a logical quantum gate for photons.

Scientists from all over the world are working on concepts for future quantum computers and their experimental realization. Commonly, a typical quantum computer is considered to be based on a network of quantum particles that serve for storing, encoding and processing quantum information. In analogy to the case of a classical computer a quantum logic gate that assigns output signals to input signals in a deterministic way would be an essential building block. A team around Dr. Stephan Dürr from the Quantum Dynamics Division of Prof. Gerhard Rempe at the Max Planck Institute of Quantum Optics has now demonstrated in an experiment how an important gate operation — the exchange of the binary bit values 0 and 1 — can be realized with single photons. A first light pulse containing one photon only is stored as an excitation in an ultracold cloud of about 100,000 rubidium atoms.

An experiment seeks to make quantum physics visible to the naked eye

Predictions from quantum physics have been confirmed by countless experiments, but no one has yet detected the quantum physical effect of entanglement directly with the naked eye. This should now be possible thanks to an experiment proposed by a team around a theoretical physicist at the University of Basel. The experiment might pave the way for new applications in quantum physics.

Quantum physics is more than 100 years old, but even today is still sometimes met with wonderment. This applies, for example, to entanglement, a quantum physical phenomenon that can be observed between atoms or photons (light particles): when two of these particles are entangled, the physical state of the two particles can no longer be described independently, only the total system that both particles form together.

Despite this peculiarity, entangled photons are part of the real world, as has been proven in many experiments. And yet no one has observed entangled photons directly. This is because only single or a handful of entangled photons can be produced with the available technology, and this number is too low for the to perceive these photons as light.

New Model Could Show That Stephen Hawking Is Right About Black Holes

One of the longest standing mysteries of black holes is what happens to stuff when it falls inside. Information can’t move faster than light, so it can’t escape a black hole, but we know that black holes shrink and evaporate over time, emitting Hawking radiation. This has troubled scientists for 40 years. Information can’t simply vanish.

Now, physicists Kamil Brádler and Chris Adami, from the University of Ottawa and Michigan State University respectively, have been able to show that the information is not at all lost, but is transferred from the black holes into the aforementioned Hawking radiation, potentially solving a long-standing mystery of cosmology.

Over 40 years ago, Stephen Hawking put forward the idea that although nothing can escape a black hole, there should be a certain amount of particles emitted from the outer edge of the black hole’s event horizon. This emission would over time steal energy from a black hole, causing it to evaporate and shrink.

Theorists perplexed

Physicists may soon know if a potential new subatomic particle is something beyond their wildest dreams — or if it exists at all.

Hints of the new particle emerged last December at the Large Hadron Collider. Theorists have churned out hundreds of papers attempting to explain the existence of the particle —assuming it’s not a statistical fluke. Scientists are now beginning to converge on the most likely explanations.

“If this thing is true, it’s huge. It’s very different than what the last 30 years of particle physics looked like,” says theoretical physicist David Kaplan of Johns Hopkins University.

Exploring phosphorene, a promising new material

RPI’s new material takes semiconducting transistors to new levels.

Two-dimensional phosphane, a material known as phosphorene, has potential application as a material for semiconducting transistors in ever faster and more powerful computers. But there’s a hitch. Many of the useful properties of this material, like its ability to conduct electrons, are anisotropic, meaning they vary depending on the orientation of the crystal. Now, a team including researchers at Rensselaer Polytechnic Institute (RPI) has developed a new method to quickly and accurately determine that orientation using the interactions between light and electrons within phosphorene and other atoms-thick crystals of black phosphorus. Phosphorene—a single layer of phosphorous atoms—was isolated for the first time in 2014, allowing physicists to begin exploring its properties experimentally and theoretically. Vincent Meunier, head of the Rensselaer Department of Physics, Applied Physics, and Astronomy and a leader of the team that developed the new method, published his first paper on the material—confirming the structure of phosphorene—in that same year.

“This is a really interesting material because, depending on which direction you do things, you have completely different properties,” said Meunier, a member of the Rensselaer Center for Materials, Devices, and Integrated Systems (cMDIS). “But because it’s such a new material, it’s essential that we begin to understand and predict its intrinsic properties.”

Meunier and researchers at Rensselaer contributed to the theoretical modeling and prediction of the properties of phosphorene, drawing on the Rensselaer supercomputer, the Center for Computational Innovations (CCI), to perform calculations. Through the Rensselaer cMDIS, Meunier and his team are able to develop the potential of new materials such as phosphorene to serve in future generations of computers and other devices. Meunier’s research exemplifies the work being done at The New Polytechnic, addressing difficult and complex global challenges, the need for interdisciplinary and true collaboration, and the use of the latest tools and technologies, many of which are developed at Rensselaer.

The light stuff: A brand-new way to produce electron spin currents

With apologies to Isaac Asimov, the most exciting phase to hear in science isn’t “Eureka,” but “That’s funny…”

A “that’s funny” moment in a Colorado State University physics lab has led to a fundamental discovery that could play a key role in next-generation microelectronics.

Publishing in Nature Physics April 25, the scientists, led by Professor of Physics Mingzhong Wu in CSU’s College of Natural Sciences, are the first to demonstrate using non-polarized light to produce in a metal what’s called a spin voltage — a unit of power produced from the quantum spinning of an individual electron. Controlling electron spins for use in memory and logic applications is a relatively new field called spin electronics, or spintronics, and the subject of the 2007 Nobel Prize in Physics.