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Despite its intensity, the gravitational collapse of certain massive stars does not produce an abundance of heavy elements.

About half of the elements heavier than iron are made by the r, or rapid, process. A nucleus captures neutrons so quickly that radioactive decay is forestalled until the neutron-heavy nucleus finally emits electrons and neutrinos and settles at a new, higher atomic number. Besides normal supernovae and neutron-star mergers, the r process is also suspected to occur in so-called collapsars. These are rapidly rotating massive stars that collapse without producing a regular supernova once they exhaust their fuel. However, simulations by Coleman Dean and Rodrigo Fernández of the University of Alberta, Canada, have now undermined that r-process conjecture [1].

A collapsar’s progenitor is massive enough that it forms a black hole. To shed its prodigious angular momentum, it also forms a thick, unstable accretion disk. During the collapse, nuclei in the stellar envelope break apart, and their protons combine with electrons in the envelope to produce neutrons and neutrinos in large numbers. These neutrons could turn the disk into a favorable, if fleeting, site for the r process to forge and disperse heavy elements—provided that this neutron-rich matter can be ejected.

When two laser beams converge on a volume of gas, their interference creates a diffraction grating made of plasma that can divert and shape a third beam.

Once a laser pulse packs more than 10¹⁸ W/cm² or so of power, its electric field strips electrons from atoms and accelerates them to near light speed. This effect could lead to compact and highly efficient particle accelerators (see Viewpoint: Shooting Ahead with Wakefield Acceleration). But for various reasons to do with pulse generation, the main pulse is unavoidably preceded by weaker prepulses, which can muddle an experiment’s initial conditions and frustrate anticipated results. Now Matthew Edwards of Stanford University, working at Julia Mikhailova’s lab at Princeton University, and collaborators have demonstrated a setup that can delete meddlesome prepulses with unprecedented effectiveness [1].

A key component of the researchers’ setup was demonstrated in 2009 [2]. Two pulsed beams of the same wavelength converged on a volume of gas contained in a cell, ionizing the gas where the beams constructively interfered. The difference in refractive index between the plasma and the neutral gas created an instant and switchable diffraction grating.

The world’s thinnest lens diffracts light of specific wavelengths instead of refracting it.

By arranging a special material in concentric rings, researchers have built the world’s thinnest lens at just three atoms thickness.

Immortality particles called quasiparticles face_with_colon_three

A collective excitation behaving as a single emergent entity, known as a quasiparticle, often becomes unstable when encountering a continuum of many-body excited states. However, under certain conditions, the result can be totally different.

Brookhaven National Laboratory researchers are working to develop ways to synchronize the magnetic spins in nanoscale devices to build tiny signal-generating or receiving antennas and other electronics.

Upton, New York — Scientists at the U.S. Department of Energy’s Brookhaven National Laboratory are seeking ways to synchronize the magnetic spins in nanoscale devices to build tiny yet more powerful signal-generating or receiving antennas and other electronics. Their latest work, published in Nature Communications, shows that stacked nanoscale magnetic vortices separated by an extremely thin layer of copper can be driven to operate in unison, potentially producing a powerful signal that could be put to work in a new generation of cell phones, computers, and other applications.

The aim of this “spintronic” technology revolution is to harness the power of an electron’s “spin,” the property responsible for magnetism, rather than its negative charge.

New research from North Carolina State University shows that unique materials with distinct properties akin to those of gecko feet – the ability to stick to just about any surface – can be created by harnessing liquid-driven chaos to produce soft polymer microparticles with hierarchical branching on the micro-and nanoscale.

The findings, published today (October 14, 2019) in the journal Nature Materials, hold the potential for advances in gels, pastes, foods, nonwovens, and coatings, among other formulations.

The soft dendritic particle materials with unique adhesive and structure-building properties can be created from a variety of polymers precipitated from solutions under special conditions, says Orlin Velev, S. Frank and Doris Culberson Distinguished Professor of Chemical and Biomolecular Engineering at NC State and corresponding author of the paper.

Polymer precipitation under turbulent flows generates soft microparticles with branched dendritic coronas and high adhesive properties.

Manchester, England— On a rare sunny day in northern England, the National Graphene Institute (NGI) here gleams like a five-story block of obsidian. Squeezed into the University of Manchester’s sprawling downtown campus, the research center is clad in almost 2000 lustrous black panels with small hexagonal perforations—an architectural nod to the structure of the atom-thin sheet of carbon that gives the building its name.

NGI exists because graphene was first isolated a short walk away in a University of Manchester lab. Andre Geim and Konstantin Novoselov presented it to the world 20 years ago this month and later won a Nobel Prize for the work. Since its unveiling, billions of dollars of R&D funding have flowed to graphene, in a global race to exploit its peerless properties. It is better at carrying electricity than any metal, a superb heat conductor, and hundreds of times stronger than steel—selling points trumpeted in the marketing materials of universities and companies alike.

Early on, researchers were not shy about promising graphene breakthroughs, with predictions that it would enable superthin rollable TVs and space elevators, and even supplant silicon in computer chips. “Expectations were very, very high,” Geim says. “The companies I was involved in were mostly based on hype.”

Quantum physicists have developed a new type of optical atomic clock, using quantum entanglement among strontium atoms to achieve unprecedented precision.

This breakthrough could significantly impact quantum computing and precision sensing, although it currently operates effectively for only milliseconds.

Quantum Advances in Timekeeping.